You can do this with Trezor. It allows you to enter a 25th word to your seed when you unlock it (it looks like you're just entering your password, but you could

You can do this with Trezor. It allows you to enter a 25th word to your seed when you unlock it (it looks like you're just entering your password, but you could enter any password), generating a whole new set of private keys. Although this makes less sense in the context of a PGP key...