Could a hardware authenticator (Yubikey) be a workaround for this? Or are there services which don't support this?
Yes, there are many which still only support SMS MFA -- and if you meant TOTP-On-Yubi, that's its own can of worms (limited size, [intentionally?] hard to sync or backup, vender lock-in?). I hope passkeys lead to brouder FIDO/U2F support.