Firemonkey mobile application high-level design best practices regarding forms / frames / styling. Delphi RIO 10.3

I'm in a phase where I need to make , for my feeling, important high-level design decisions for my application. For the past few days (!), I've been doing some cycles of investigation, test, discover showstoppers and restart...

As I've also benifit many times from others people work in the past, I thought I spend the time to share my outcome. Maybe it can help someone to save some time. Or have some valuable feedback from the experts out there :-).
I'm answering my own question below. And I'm welcoming comments and especially warnings :-)

Regards Dirk