While I agree that MacOS will not be likely to come to iPads, I still believe there is a good opportunity for PG Music in the Apple Mac and iOS/iPadOS space for a version of "BIAB Lite" that could be developed using the latest shared development technologies.
It wouldn't initially need anything like the huge range of features of the existing product, and could even have an option of compressed audio for space considerations.
It might also put PG Music on a good track for future BIAB development as they get experience by starting something using 2022 technologies, rather than trying to wrangle a very old code base onto Apple Silicon natively.
In my opinion there is a huge amount of value in RealTracks and RealDrums IP that could be realised.