Have you tried picking a project that might have a lower bar for contributing, or is closer to your skills? Of course, this doesn’t help those projects be more accessible, but it could help develop your confidence until you’re ready to work on those (and hopefully change their culture!)
This seems like kind of a weird approach. I've never thought to myself, Hmm, I need to go out and pick a project to contribute to. If I have a patch to send out it's because I'm already using the project for something and I need to upstream a change.
Think about why you are contributing to a project: Are you adding a feature that it lacks but that you need? Are you fixing a bug that hampering your other work? I wouldn't just pick a random project and file a PR just because I want to contribute something to open source. I'd start with a project I already use, where I have a problem I have to solve, solve it, then contribute the patch.
It seems backwards to start with "I want to write a patch to something" and then go out and find a project to patch.
Not in general. I have never in my life experienced the "smacked down in PR for some arcane technical reason, likely with a rude comment" that the O.O.P. wrote. Although I wouldn't let that bother me. If someone doesn't want to merge a patch I send them, that doesn't even remotely hurt my feelings.
You can "Contribute to Open Source" without your contributions being accepted/merged.
