Something you have + Something you know. SOP.
replyGrapheneOS has Touch ID and a passcode as an option.
replyAnd what happens when your Touch ID stops working I find biometrics to be quite fragile.
replyYou still have a separate password that authenticates you without biometrics.
replyThe touch + passcode is nice because even if someone watches you enter your passcode it won't matter unless they can spoof the fingerprint reader too, which is highly unlikely. And you can use a much shorter passcode for convenience.
Wash your hands? /s
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