The introduction of a plugin system seems interesting here, though it's still alpha and basically looking for feedback from would-be plugin developers
AFAICT, there's no established way for a plugin to surface affect the UI, which would be a somewhat unwieldy problem anyway due to the apps and frontends ecosystem. Probably the best path for any plugin that provides a UI would be to have a system for aggregating links to plugin UIs.
With something like that in place, plugins and other services that just use the DB/API, could really go a long way to filling these holes, if they haven't already.
So it seems that the work needed here is perhaps "distribution" work ... where there's a more "plug and play" Lemmy distribution with plugins etc bundled?