I've been in the fediverse for a few years now most of the time on Mastodon.
The missing likes and replies you are reffering to are probably a federation issue. Smaller instances tend to lack some content. There are ways for admins to cope with that though.
I haven't really experienced this issue on any Instance with a few hundred users though and follows should work regardless. I've had similar issues with Misskey.
I want to make clear that this is not a design choice. Mastodon doesn't change those numbers randomly on purpose.
You also mentioned that it was hard for you to find content you like andadmittedly its harder than on Twitter but following hashtags is a good start.
Mastodon can be very rewarding if you are into micro blogging but Lemmy offers a different kind of experience that can't be compared imo. Both are great options to browse the fediverse.
Sorry this text turned out longer than intended. Got carried away.
Yes. Friendica for example supports Activitypub but also the diaspora protocol