

Subscribe to all of them. It won’t be a problem.
It’s like if you followed #s of the same thing on Instagram, twitter, mastodon, bluesky, and whatever the equivalent of # is on Facebook, then a reddit sub with the same name. Different populations and user bases, but that’s a good thing.
There’s some degree of consolidation that happens, particularly when one community is on a bigger instance and would be better served by being hosted elsewhere. But there’s not really any barriers to using multiple. If you crosspost, you have better chances of it being seen anyway, and you’ll get access to any responses. If you’re wanting to comment, then the OP that crossposted is going to get your response no matter which ones it’s in.
Only drawback is that your comment in one won’t show in the others unless you copy/paste it. Which is perfectly valid if you want to, but most people would see your comment eventually anyway, so the conversation will still happen if it would have in the first place.
I kinda had issues adapting to it myself, but now I tend to prefer it when communities are spread out, because every instance has its own vibe usually. So you get different kinds of discussions than you would if there was only one community on one instance.
Some subjects end up needing a single community just to make it easier to find, but it’s pretty rare imo.
Definitely sounds more like a pixelfed use case.
But, any instance can work, just communicate with the admins and make sure it’s cool, then create a community and set it to mod only posting. My cousin used to do that, and it worked fine.
There’s a couple of communities set up like that as well.
Generally, you won’t look like you’re spamming posts, unless you’re spamming posts. Like, set yourself a time limit between posts, and spread them out.
or do single posts via topic on your personal C/, and include related links/media as comments the way forums did stickied posts for things. Helps keep from reposting stuff too, since you can scroll a thread easier than a C/, on most apps.