I run a few groups, like @fediversenews@venera.social, mostly on Friendica. It’s okay, but Friendica resembles Facebook Groups more than Reddit. I also like the moderation options that Lemmy has.
Currently, I’m testing jerboa, which is an Android client for Lemmy. It’s in alpha, has a few hiccups, but it’s coming along nicely.
Personally, I hope the #RedditMigration spurs adoption of more Fediverse server software. And I hope Mastodon users continue to interact with Lemmy and Kbin.
All that said, as a mod of a Reddit community (r/Sizz) I somewhat regret giving Reddit all that content. They have nerve charging so much for API access!
Hopefully, we can build a better version of social media that focuses on protocols, not platforms.
I’m also a recent transplant. I too find the (current) lack of activity in certain niche areas disappointing, but I’m hoping that’s temporary. I hope discussions of some of those topics can survive the inevitable fragmentation among instances.
On the other hand, I’ve installed Jerboa on my phone, and it’s working very well. Now I’ve just got to get busy participating in those niche communities–could be tricky, 'coz the ones I often liked best were the ones I knew the least about. I enjoyed learning from people who already knew the ropes.