I want to deterministically generate mnemonic phrases (BIP39 and Monero) with a Trezor, similar to how addresses are derived from a mnemonic phrase (this is just an analogy, and not a perfect one, I know).
is there a (quasi) standard way of doing this?
This is what BIP-85 is about, and there is an open issue about it, but it is not currently a priority.
So as of now, you can’t do this on a Trezor.
What you can do, of course, is export some sort of deterministic randomness, e.g., by using trezorctl crypto encrypt-keyvalue, and use that randomness as an input to a mnemonic generator on your PC.
trezorctl crypto encrypt-keyvalue
great, I’m looking forward to BIP85 in trezorctl!
that command is a good idea too.