Add option to encrypt the trezor seed with a password of the user’s choosing.
It would be ideal if the encryption engine generated a decoy seed resulting from encryption of the original seed, as it could be used for plausible deniability.
It would be better if this decoy seed was a valid BIP39 seed so that whoever finds this encrypted seed, thinks it is the user’s real seed, he could use this encrypted seed as decoy, keeping funds in case of duress.
It should also be possible to export the encrypted seed to the SD card slot, so the user could store this encrypted seed digitally, as in theory, it would be protected with a strong and secure password.
If the idea matures, you could add this idea by creating a new SLIP and later be adopted by more wallets (it would be better, because if the user loses the trezor, he could restore it in another wallet that has this feature of deciphering the seed).
Therefore, the user could choose to encrypt the seed with this feature I suggested or use just the passphrase as an additional layer of security, or use both.