I likewise have a similar background to the OP. I wouldn’t say I struggled (thanks to the Matrix chat room), but the docker instructions straight up didn’t work a couple of days ago. I and another guys submitted a couple of PRs and I think the instructions should at least work for common setups now, but the edges are very rough.
By far the best way to contribute IMO is submitting PRs. The devs seem very willing to take contributions without making you jump through hoops.
You need the whole link, including the “https://reddit.com/” part: https://www.reddit.com/r/ModCoord/comments/1401qw5/incomplete_and_growing_list_of_participating/
Someone put together a cool visualization of this too: https://reddark.untone.uk/ Several subreddits are already private.