Yes, you can generate PGP/GPG keys and also SSH keys with Trezor and Ledger. If you use a passphrase then the GPG or SSH key generated is different than the one you would get with the seed without the extra passphrase.
Trezor and Ledger can also do U2F.
You can do anything that YubiKey and others do, plus cryptocurrency, with a Trezor or a Ledger.
It’s cool to hear that, but I wouldn’t trust a Trezor or Ledger for both crypto and gpg/ssh keys. They are completely different things and is the same as giving both your money and your identity to someone if they steal it somehow(even in a encrypted state, I think it not worth it).