while yes it’s cool that I can talk to Lemmy from my Mastodon account, it’s quite a clunky experience

I do wish they were slightly more interoperable. It's currently very hard if not impossible to discuss Mastodon posts directly within Lemmy, and likewise you can't make a Mastodon-style post to your personal Lemmy profile. These may seem like unimportant changes, but I think much of that stems from still viewing these services from the frame of the limitations of what they are based on. They could be so much more!

Lemmy itself has big problems with the interoperability of servers. There are two major issues I see with the way communities are structured. The first is that listed subscriber numbers are for your server only, which makes the entire ecosystem seem way less lively than it actually is, which has the effect of making it even less so. Subscriber numbers should be fed in from a community's home server.

The second is that there are many redundant communities, which makes it difficult for onboarding new users. There should be some way to group like-communities into super-groups based on topics. That way community leaders have the ability to easily aggregate similar content, rather than leaving it to the user to figure out, and you could opt-out as a user by simply not subscribing to the super-group community.