Reddit, discord, forums, twitch, youtube etc. Depending on the hobby, certain sites are better than others, for instance, reddit is much better at selecting meme content than serious, long-form discussion, but it can serve as aa hub for links to different communities and resources. Discord can be nice when you find a small, niche community and its quality usually drops the more people join. Forums are the best for long-form, serious discussion, as threads are expected to stay a long time and people are expected to put in at least a minimal amount of effort when writing a reply (although, this doesn't stop normalfags from inflating their post count with one liner "thanks, this is great" filler). Twitch and youtube communities always organize around a particular content creator, so they usually turn out to be more about the creator than the content.
Twitch has a lot of people streaming themselves doing a particular hobby, like drawing or japanese printmaking. I like browsing through Science & Technology section on twitch and find these small channels that stream programming. Sometimes I watch, sometimes I just have it in the background while I work on my own stuff.