Some websites already do something similar: if you are logging in from an "unrecognized" (unfingerprinted) browser, they might force you to 2FA authenticate and

Some websites already do something similar: if you are logging in from an "unrecognized" (unfingerprinted) browser, they might force you to 2FA authenticate and then give you have the option to "trust this browser" for future logins. You might still need to log in with your password, but not 2FA. Of course, that fingerprint can break when your browser auto-updates to a new version.