I dunno about autonomous, but it is happening at least a bit from human pilots. I've got a fork of a popular DevOps tool that I doubt the maintainers would want to upstream, so I'm not making a PR. I wouldn't have bothered before, but I believe LLMs can help me manage a deluge of rebases onto upstream.
same, i run quite a few forked services on my homelab. it's nice to be able to add weird niche features that only i would want. so far, LLMs have been easily able to manage the merge conflicts and issues that can arise.
The agents are not that good yet, but with human supervision they are there already.
I've forked a couple of npm packages, and have agents implement the changes I want plus keep them in sync with upstream. Without agents I wouldn't have done that because it's too much of a hassle.