Yubikey and nitrokey are two usb keys that supports Gnupg, it should be possible for the live installer to support them and use those to set up unlocking of the system.
It might be feasible to include the possibility to create GnuPG keys on such devices if that function is also implemented in the live installer.
Documentation:
https://docs.yubico.com/
https://docs.nitrokey.com/