I've been trying to make a parts list, but I've run into a couple of roadblocks with the PCB and the buttons, both parts that arent available anymore, title says the rest

So I found the guide and parts list from 2016, and I'm wondering if that guide still works.
If so, I'm wondering how to get the button pcb and the other parts that don't exist anymore. Maybe even create them myself if there is a guide on how to do so.