Seems to me the whole argument boils down to “they (the passkeys) are generally saved in proprietary non-communicating stores”, which is fair. But then the problem is not the passkey, it’s the fact that we (as usual) give all our stuff to corps. It’s the eternal struggle of easy of use vs. better security.
I host my own vaultwarden btw 😊
Just as a test, can you try ubuntu? It looks like you tried “enterprise” distros, may be worth with a more generic one, maybe they have a different set drivers.
Also, can you try running lspci command, maybe it shows any devices it doesn’t recognize (so you can investigate those specifically). Pretty sure there is also a gui app about drivers, but I’m not familiar with kde.