According to this article, Samsung doesn’t block that, it’s just badly implemented:

https://9to5google.com/2023/07/27/galaxy-z-flip-5-google-wallet/

I mean that makes sense. Samsung doesn’t bill it’s front screen as a full phone, it’s supposed to be just a window for quick info at a glance. It’s probably more just Google hasn’t made its app compatible with the flip’s cover screen. In any case at this point the screen on the flip 5 is actually a decent size so it should be able to run any app like the razor.