Normally this sort of organisation is called a “not for profit”. It acts like a company in every respect but doesn’t do more than pay for its own use. Examples are semi-public services such as “Transport for London” etc. in terms of org or dot com, I think you can use either.
I’ve been on Reddit for 16 years and I’d say yes it’s very similar. Like Reddit back then it was very tech focused and quite liberal.
I do think people are a bit more vicious online these days than they used to be and a bit more polarised.
From a content perspective there used to be more blog content than tech news content, but it’s fairly similar. What I like about Lemmy is it’s far less commercial and the conversation is more genuine.
However I don’t think Lemmy will become Reddit in 15 years, I think it may languish in eternal obscurity and I’m actually okay with that.
Reddit exploded when Digg crumbled and the same could happen with Reddit crumbling but idk, there seems to be some stickiness to Internet websites these days.