Exactly the answer I had in mind. It's something you can do on your own time and in your own space, but it also creates opportunities to interact with other hobbyists.

Something I hate as an introvert - and notice in many other introverts - is the pain of making idle small talk. Having a common interest as a reason to talk to other people feels much more natural to me and is great as an entry point for introverts wanting to get to know other people without it feeling forced.

You can do it for wargaming like 40K, but also for TTRPGs like DnD. Sometimes I just paint models for the hell of it that I never intend to use in any game. You can also branch out from making models to building terrain and scenery - there's loads of great tutorials on YouTube.