You could check out Frappe Drive (and Frappe, the framework it’s built on, it’s pretty awesome). They aren’t accepting contributions at the moment but I’m sure that’ll change once it’s out of beta like with the other frappe apps. There’s also Raven messenger also built on Frappe and you can use the two together (but without any real integration between the two yet, but that’s on the roadmap on the Raven side).

I’ve spent a lot of time researching alternatives and NextCloud is the only one that does everything it does in one place. I’ve dug into the code a lot to find places to make it work faster and came out confused and mostly empty. It’s also federated, and I think it’s the only FOSS file sharing platform that is. It’'s a very mature application so you’ll be hard pressed to find features that are missing, but also to find things that could be further optimized without ripping out major chunks of the application which are likely interconnected with other major chunks of the application. For my personal use NextCloud instance I’ve resorted to just completely deleting the database and installing everything fresh between major versions, then just rescanning my local folder.