Mate your plan sounds like a good one, unfortunately, I cant help you directly, but I can tell you what I would do ( Which you may have already considered )
I did a quick interwebs search, and When I first saw the App, I thought tasker might be a solution, scan your implant, tasker script, door opens BUT if you have your phone, it automatically opens…
Next, I thought, I would be opening up both the lock and the keypad and finding the Lock / unlock points on the board, and throwing an xAC or similar onto one of those.
It’s not as elegant as your plan, but it is a Cheap, Simple solution.
Anyway, I didn’t want to leave you hanging without an answer, although you still didn’t get one, there is some food for thought
As a side note, this Wyze lock, appears to be a cheap ($100) multiple lock type compatible, with the potential to be a good base to build off for the community lock project ( So that may be your alternative solution )