There is a way to place the secret file (corresponding to the password) on a dedicated USB stick and have a script attempt to Mount it at boot to unlock the partition. If the USB stick is not found, it will revert to the password prompt. Perhaps this is the best of both?
Make sure not to leave the USB stick plugged in, but rather only take it and and plug it in to boot then safely store it once booted, otherwise you are probably defeating the purpose of having an encrypted partition to begin with.
I’ll add a link to read more about it shortly.
Edit: here is one example to set it up (including to auto-decrypt ZFS) https://www.youtube.com/watch?v=7xOLxCwdi-I
I think that’s what we see with apple silicon, right?