I have the feeling you’re trying to solve a problem that does not exist, and you’re throwing out the baby with the bathwather.
Your solution does not allow for easy updating, is hard/impossible to use in automated deployments and is easy to circumvent.
Deploy keys and a Git repository will suffice and don’t have the above drawbacks.
Again, my tip: validate your business model first and focus on the value. First make a plugin that everyone wants to buy, then solve the problem how to sell it.