My passkeys are stored in keypass, which I share between multiple devices. Phone, home servers, desktop pc and a flashdrive that stays in my car.

Obviously the flash drive needs to be manually updated but the other devices use syncthing to keep everything up to date.

I get there are some people that have concerns over such a configuration but I'm happy bopping away knowing that if my phone dies, I've still got access to accounts / can easily be back up and running on a fresh device.