That's really nice. What tools are you using? How do you manage adding and removing keys? How many people and devices are involved? > Where does GitHub come in

That's really nice. What tools are you using? How do you manage adding and removing keys? How many people and devices are involved? > Where does GitHub come into all this? To maintain verification dynamically for team members. Maintaining lists are otherwise (and in your example, I think) a N^2 maintenance task. Everyone needs to update their pubkey list when a team member adds or removes a device.