The way I see it, Lemmy and the Fediverse as a whole is a big step back to the golden age of the internet before social media became the cancer that it is today and the internet wasn’t controlled by a few big corporations. A big part of that, to me at least, is that you could customize your accounts, home pages, profiles, and so much more. I think Lemmy could greatly benefit from a more expansive profile that lets you customize color, font, design, play audio, and other things like that. I think optimizing the site and adding in more essential features should come before anything like this, but I think it would really enhance the overall experience!
Lemmy is on version 0.18, the main focus of development will be core functionality. Now more Developers are getting involved stuff like this will pick up for sure, but the system as a whole is a work in progress. In the mean time you could discuss the types of modifications you like and even add enhancement suggestions to the appropriate Github, and if you have the development skills, get involved yourself.
I’m not super concerned right now but I’m definitely going to be dissapointed if I don’t see it in the future. But I still get the joy of seeing this place grow since I joined a couple weeks ago