[falsedan]

That's what we did at my last workplace; 800-odd devs, 3000-odd repos, and a service we wrote to record and gather all the ownership metadata (which team owns this repo? where can I contact them? who should be on the code reviews? how do I page them? which project should tickets be created in?)

It was a gigantic pain trying to find owners for half-dead repos for services still running and in use, where the original authors had left years ago & from teams 4 or 5 restructures ago. The one thing I learned was: never make a user the owner of a repo (unless it is in their personal space), always find a team to accept responsibility for it.