This prompted me to check, and seems like KeePassXC supports storing passkeys, at least if you use the browser extension and enable a flag in its config. Until now I had thought it only supported unlocking your database with passkeys, I didn't know about it being able to actually store them.

I guess I'll try setting them up on some unimportant website to see for myself what all the hype is about.

Whatever you do, don't export passkeys with KeePassXC. It exports them in the clear. It's not considered kosher to export passkeys from any credential manager's data store anyway.