You answered it yourself (last paragraph). The main point is everything is in FOSS but not packaged like chromeos.
I strongly want bluefin/silverblue/bazzite etc to succeed but even installation is PITA. UI is not really that polished. Whether or not great one like proper integration (a.k.a like Apple) like passkey in Google Chrome/Android etc.
- Installer of bluefin etc takes super long - issue with btrfs - no idea. Dev says upstream issue - not us. - flatpak is still pain for normies - we wanted to deploy it to a large compter pool - ecosystem is controlled by Google. So fewer failures with hardware.
- And polish (like you say). Why can't <distro> make it so that uefi etc is hidden?
- Normies expect sleep to work. This is still not perfect with distro (not their fault).
Many including me - want OS to be like an appliance. Just works.