I'm not sure, but all issues containing the word moderation can be found here: https://github.com/LemmyNet/lemmy/issues?q=is%3Aissue+is%3Aopen+moderation
(I looked a bit and couldn't find one specifically for it, but I remembered this issue I was linked once which is also interesting for us: https://github.com/LemmyNet/lemmy/issues/2414)
@[email protected] might be able to tell you more about that, but there's also stuff outside of coding they could use help on, like documentation. I think opening issues is also good, so that someone can take a look at it.
But it does all require knowledge of how git repos work.