With the U2F authentication, is it possible for the trezor model T display your authentication code? If not, does that mean the site/application you are using need to explicitly support hardware u2f? If it does support for displaying the code, is there a way to import existing codes from an authentication app?
Neither Trezor One, nor Trezor T reveals any authentication code on its display. See how it works https://www.youtube.com/watch?v=-3YsZHu8o74
You can use U2F with any website supporting it. Check out services using U2F at twofactorauth.org or dongleauth.info.
In order to get even more information see following links:
Does the U2F work with android?
Based on information I have, it should work as well.