I have nextcloud and don’t even use it for file management (in that sense). It’s a joplin sync server, I use the Cookbook app probably as my most used thing on nextcloud, I use phonetrack, sync tasks.org to it for task management, use the Bookmarks app for keeping track of links.
Plus I never feel bad for running extra services. Idle services use a pretty tiny amount of resources. I had 15 or 20 on a Raspberry Pi 4 before I switched to using an old laptop.