Qt was built with forced debug info, which leads to huge library (.so) files that cannot be used for deployment without further processing.

Forcing debug info is fine, but it should be accompanied by -separate-debug-info, so the debug information is separate from the actual dynamic libraries. That is how it is done on Windows (because that is just how debug info works on Windows), and also how it would be done on macOS (with separate .dSYM bundles).