qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in ""

Configure summary: 
 
Build type: openbsd-clang (x86_64, CPU features: mmx sse sse2) 
Compiler: clang 10.0.1 
Configuration: sse2 aesni largefile rdrnd rdseed shani x86SimdAlways shared shared rpath release c++11 c++14 c++17 c++1z concurrent dbus reduce_exports redu
ce_relocations stl 
Build options: 
 Mode ................................... release 
 Optimize release build for size ........ no 
 Building shared libraries .............. yes 
 Using C standard ....................... C11 
 Using C++ standard ..................... C++17 
 Using ccache ........................... no 
 Relocatable ............................ yes 
 Using precompiled headers .............. no 
 Using LTCG ............................. no 
 Target compiler supports: 
 SSE .................................. SSE2 
 AVX .................................. <none> 
 AVX512 ............................... <none> 
 Other x86 ............................ AES RDRAND SHA 
 Intrinsics without -mXXX option ...... yes 
 Build parts ............................ libs examples tools 
Qt modules and options: 
 Qt Concurrent .......................... yes 
 Qt D-Bus ............................... yes 
 Qt D-Bus directly linked to libdbus .... yes 
 Qt Gui ................................. yes 
 Qt Network ............................. yes 
 Qt Sql ................................. yes 
 Qt Testlib ............................. yes 
 Qt Widgets ............................. yes 
 Qt Xml ................................. yes 
Support enabled for: 
 Using pkg-config ....................... yes 
 udev ................................... no 
 Using system zlib ...................... yes 
 Zstandard support ...................... yes 
Qt Core: 
 DoubleConversion ....................... yes 
 Using system DoubleConversion ........ yes 
 GLib ................................... yes 
 iconv .................................. no 
 ICU .................................... yes 
 Built-in copy of the MIME database ..... no 
 Tracing backend ........................ <none> 
 Logging backends: 
 journald ............................. no 
 syslog ............................... yes 
 slog2 ................................ no 
 PCRE2 .................................. no 
 Using system PCRE2 ................... yes 
Qt Network: 
 getifaddrs() ........................... yes 
 IPv6 ifname ............................ yes 
 libproxy ............................... no 
 OpenSSL ................................ yes 
 Qt directly linked to OpenSSL ........ yes 
 OpenSSL 1.1 ............................ yes 
 DTLS ................................... no 
 OCSP-stapling .......................... yes 
 SCTP ................................... no 
 Use system proxies ..................... yes 
 GSSAPI ................................. no 
Qt Gui: 
 Accessibility .......................... yes 
 FreeType ............................... yes 
 Using system FreeType ................ yes 
 HarfBuzz ............................... yes 
 Using system HarfBuzz ................ yes 
 Fontconfig ............................. yes 
 Image formats: 
 GIF .................................. yes 
 ICO .................................. yes 
 JPEG ................................. yes 
 Using system libjpeg ............... yes 
 PNG .................................. yes 
 Using system libpng ................ yes 
 Text formats: 
 HtmlParser ........................... yes 
 CssParser ............................ yes 
 OdfWriter ............................ yes 
 MarkdownReader ....................... yes 
 Using system libmd4c ............... no 
 MarkdownWriter ....................... yes 
 EGL .................................... yes 
 OpenVG ................................. no 
 OpenGL: 
 Desktop OpenGL ....................... yes 
 OpenGL ES 2.0 ........................ no 
 OpenGL ES 3.0 ........................ no 
 OpenGL ES 3.1 ........................ no 
 OpenGL ES 3.2 ........................ no 
 Vulkan ................................. no 
 Session Management ..................... yes 
Features used by QPA backends: 
 evdev .................................. no 
 libinput ............................... no 
 INTEGRITY HID .......................... no 
 mtdev .................................. no 
 tslib .................................. no 
 xkbcommon .............................. yes 
 X11 specific: 
 XLib ................................. yes 
 XCB Xlib ............................. yes 
 EGL on X11 ........................... yes 
 xkbcommon-x11 ........................ yes 
QPA backends: 
 DirectFB ............................... no 
 EGLFS .................................. yes 
 EGLFS details: 
 EGLFS OpenWFD ........................ no 
 EGLFS i.Mx6 .......................... no 
 EGLFS i.Mx6 Wayland .................. no 
 EGLFS RCAR ........................... no 
 EGLFS EGLDevice ...................... yes 
 EGLFS GBM ............................ yes 
 EGLFS VSP2 ........................... no 
 EGLFS Mali ........................... no 
 EGLFS Raspberry Pi ................... no 
 EGLFS X11 ............................ yes 
 LinuxFB ................................ no 
 VNC .................................... yes 
 XCB: 
 Using system-provided xcb-xinput ..... yes 
 Native painting (experimental) ....... no 
 GL integrations: 
 GLX Plugin ......................... yes 
 XCB GLX .......................... yes 
 EGL-X11 Plugin ..................... yes 
Qt Sql: 
 SQL item models ........................ yes 
Qt Widgets: 
 GTK+ ................................... yes 
 Styles ................................. Fusion Windows 
Qt PrintSupport: 
 CUPS ................................... yes 
Qt Sql Drivers: 
 DB2 (IBM) .............................. no 
 InterBase .............................. no 
 MySql .................................. yes 
 OCI (Oracle) ........................... no 
 ODBC ................................... no 
 PostgreSQL ............................. yes 
 SQLite2 ................................ yes 
 SQLite ................................. yes 
 Using system provided SQLite ......... yes 
 TDS (Sybase) ........................... yes 
Qt Testlib: 
 Tester for item models ................. yes 
Note: -headerdir is not a subdirectory of -prefix. 
Note: -docdir is not a subdirectory of -prefix. Note: journald, syslog or slog2 integration is enabled. 
If your users intend to develop applications against this build, 
ensure that the IDEs they use either set QT_FORCE_STDERR_LOGGING to 1 
or are able to read the logged output from journald, syslog or slog2. Qt is now configured for building. Just run 'gmake'. 
Once everything is built, you must run 'gmake install'. 
Qt will be installed into '/usr/local/lib/qt5'. Prior to reconfiguration, make sure you remove any leftovers from 
the previous build.

$ qtdiag-qt5|grep plugin
 PluginsPath: /usr/local/lib/qt5/plugins

$ ls /usr/local/lib/qt5/plugins 
PyQt5 kauth playlistformats
audio kcm_kio.so position
bearer kcm_trash.so printsupport
designer kcm_webshortcuts.so qmltooling
egldeviceintegrations kf5 sensorgestures
gamepads mediaservice sensors
generic org.kde.kglobalaccel5.platforms spellcheckplugin.so
geoservices platforminputcontexts sqldrivers
iconengines platforms texttospeech
imageformats platformthemes xcbglintegrations

$ dragon
qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in ""
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.[1]
28012 abort (core dumped) dragon

$ export QT_PLUGIN_PATH=/usr/local/lib/qt5/plugins/
$ dragon 
QStandardPaths: XDG_RUNTIME_DIR not set, defaulting to '/tmp/runtime-rsadowski'
kf.crash: Could not find drkonqi in search paths: ("/usr/local/bin", "/usr/local/lib/libexec", "/usr/local/libexec")
... dragon starts fine