Right now the user count Lemmys is comparatively tiny when held up against reddit - but the user count isn't the thing that makes a social media site, it's the engagement
So even if you're used to lurking, try to get a little more active! Post memes, vote on posts, talk in the comments, whatever!
If people come here and see activity, content, and discussions, they're more likely to stay and contribute their own - if they come and see a ghost town, they'll just go back to reddit
That's what I'm doing on mobile, but I'm coming from relay where things were a bit more compact and smooth. I imagine things will get more developed as time goes on.
Jerboa is the only one so far, and I'm enjoying it. I wish there were more instance options available for signing in, but I'm sure that will come in due time.
If i understand you correctly: you are not limited to the small instance dropdown list in Jerboa, you can just type your own instance name in there to log in to it. That's what I did at least. If you mean more instances in general should be available in Lemmy: agree :)