[tor-onions] Run onion on boot

Hello, With software like dropbear-initramfs, cryptsetup-initrafs and others you can remotely unlock a server that has a LUKS-encrypted root partition. That is possible because there is an SSH server running in its unencrypted boot partition. I would like to have an onion service running in the boot partition too, that way I could remotely unlock the root partition without caring about ports, DNS, etc. How could I make it? Any advise, suggestion or step-by-step guide would be very much welcome, but please have in mind that I am not a developer... Thank you very much!