I agree. I use passwords with TOTP whenever possible. Passwords in a locally stored database (such as KeePassXC) can be easily shared. TOTP using Google Authenticator can also be easily shared, not just with my partner, but also among my own devices. Right now I see this as a much better, simpler, and much easier to understand option. BTW, the "easier to understand" is a big feature. Passkeys seem to be complex; just look at all the arguments about them in these comments. And where there is complexity there is vulnerability.

1Password family plan, and I assume similar cloud password managers, let you organize passwords/TOTP/Passkeys into vaults, and you can put credentials you want to share with other family members here.

You can store passkeys in a password manager where they're either in a full-time shared config or there's some configuration that allows access if something happens. (e.g. Emergency Kit for 1Password, legacy contact for Apple account, etc.)

Add your partner's passkeys to your accounts, then you can both login. Or put some Yubikeys in a safe that can be accessed if needed.