Investigate and compare the prototypes created with

• Windows QTBUG-133867
• Apple QTBUG-133869
• Android QTBUG-133872

Is there a common subset of concepts/features? Can these features be hidden behind a common API (except keys, etc.)?

Define a common API that fits to all native push notification frameworks. Implementation can be simple at this point: You can use a common header file that defines the interface and one implementation file for each platform that implements the interface with native functions.

Compile the library into a dll so you can use it in multiple test applications / presentation applications.