The only thing that will cause gitea to fail, as far as I can tell, is the hardware. It's basically a daemon on top of the linux kernel.
Stand on the shoulders of giants.
When you can.
Actually,data gravity is the issue, not features. https://github.com/go-gitea/gitea/pull/18165 needs to be merged to be able to leave Github.
I think the code an pull requests are easy migrated manually. The 2k open issues would have to be cleaned up first. Then migrate the remaining issues via api. One issue could be the non existing user on the import side.
Is there another pithy term that means this that I can use?
It is a lot faster and lighter than Gitlab, but I don't really care about that for something like this. Gitlab is fast enough, and since I run it on a dedicated server, I don't really care how much memory and resources it's using as long as it doesn't exceed the limits of the server.
EDIT: to be fair though, I haven't used gitea in at least a year. Things might have improved in that time.