Thanks for the suggestions. I have already managed to boot SkySigner USB OS but it shuts down shortly after starting. I have been trying to figure out whether the problem comes from the boot process or something in my own startup scripts. I will check the boot messages and logs you mentioned.
The NIP-49 suggestion is interesting too. One of my goals is to keep the vault locked until the user enters their password. I am also working on what happens when the USB drive is removed and inserted again without restarting the entire system. That part is proving to be one of the more difficult challenges.
