You'd want to know how it handles trusted exec. You'd want to know how Linux and BSD both work, and how updates will work, and how independent firmware can be written and certified.

How it works, kind of follows its own pace. Being able to manage heterogeneous CPU architectures, that's the first thing which says "has an advantage in the marketplace"

I imagine like UEFI its FAT fs.

FAT is the universal lowest common denominator, so yeah, probably. On the other hand, as the Chinese government has chosen to shed reliance on Western stuff (including software), I imagine that unlike UEFI, UBIOS won't be using PE executables; probably ELF.

Very early days on this it seems. The released spec so far only being 64 pages, must just be a high level summary of their goals so far? Maybe we see it in use in 8-10 years? https://www.gccorg.com/article/69/426.html