Prusa3D (there’s a community, but it has no posts yet), Mopar, Roborock, Green Mountain Grills are a few examples. Most the communities I follow on Reddit are here but just not as active yet.

Ones for various hobbies and electronic gadgets.

I’ve found my Reddit activity to have plunged since discovering Lemmy. I mostly check Reddit now for niche subs that don’t have an equivalent yet.