I use passkeys via KeepassXC (on Windows & Linux) and KeepassDX (Android), in which case Passkeys are essentially an upgrade:

1. Since I use a password manager anyways, the difference in where they are stored is nil.
2. As I use KeePass databases I remain in control.
3. Auto-fill is in my experience more flaky than passkey prompts, though it would be nice if KeePassXC could be a native provider, like KeePassDX is on Android nowadays.
4. Passkeys are generally more secure, as the key itself never leaves the device (only a challenge is performed to verify ownership of said key) unlike passwords. Passkeys also tend to be longer than passwords.

The only downside is that you need access to the database to login - unlike with passwords where it is cumbersome, but still reasonably possible to enter it manually.

I wouldn’t want my keys to be wholly linked to my device (problematic if I lose it, or it breaks) or be reliant on Google’s - or other big tech - password managers either.

It is not just him, but also the people he is trying to reach. Even if he gets assistance & the resources to set up an independent platform for this, he still has to get people to use it - which is a much higher bar to meet.