On the topic of self-hosted file manager apps, I've really liked "filebrowser". Pair it with Syncthing or another sync daemon and you've got a minimal self-hosted Dropbox clone.
Same. Just recently switch over to filebrowser-quantum. Can’t quite endorse it yet, but it’s promising so far (setup in a docker compose was a bit like wack-a-mole, but so was the original) https://github.com/gtsteffaniak/filebrowser
* https://github.com/filebrowser/filebrowser
* https://github.com/hurlenko/filebrowser-docker