MAUI Testability

[Kebechet]

Right now when you add InAppBilling Nuget into your MAUI project, the project wont be testable.
Because of:

error NU1202: Package Kebechet.Maui.RevenueCat.InAppBilling 1.0.5 is not compatible with net7.0 (.NETCoreApp,Version=v7.0). Package Kebechet.Maui.RevenueCat.InAppBilling 1.0.5 supports:
error NU1202: - net7.0-android33.0 (.NETCoreApp,Version=v7.0)
error NU1202: - net7.0-ios16.1 (.NETCoreApp,Version=v7.0)
error NU1202: - net7.0-maccatalyst16.1 (.NETCoreApp,Version=v7.0)
error NU1202: - net7.0-windows10.0.19041 (.NETCoreApp,Version=v7.0)

When I tried to add .NET7 as another TargetFramework I got:
<X> must have an implementation part because it has accessibility modifiers.

The reason behind it is that main MAUI app has to add pure .NET7 framework, so that unit-test library can link it. But this is not currently possible in library projects like this one. Apparently this should be fixed in .NET8:
dotnet/maui#3552
dotnet/maui#14847