I used to maintain those KXT 308 systems I probably wired some door openers.
My Raspberry Pi Asterisk PABX has 10 relays connected to the GPIO pins using one of these cheap Chinese boards.
A further two pins can be used for doorbells or alarm inputs
It was an interesting exercise when I did it in 2017 but although the code is still in place on my system I have not found a use for it other than its own novelty.