Lære

Yes I just meant write a simple web page so they find all the apps, since you’re running a webserver anyway. If it’s just files they need, use samba shares. The only fiddly bit you could encounter with Samba is getting the permissions correct.

By CLI I meant SSH into your server to set up containers, fix problems, install new things, instead of relying on OMV/plinth/casaos/umbrel interface. I think it’s better because you’ll never run into things the front-end you chose does poorly or not at all, and you’ll know how things work better.

My first server had Synology DSM and the second OMV, I’m not against it entirely. If you think you can’t or don’t want to manage a system without them, they’re fine. But if you can you have more control.

No experience with Umbrel or CasaOS. But headless and install your own stuff is often better, your users don’t have to use CLI, just have a startpage for them with links to the apps you have.
I personally use Freedombox, Debian’s own self hosting solution. It does run Home Assistant and Nextcloud in Podman, but doesn’t have a web interface to add other containers. The rest of its apps aren’t in containers. I only use it because it has reasonable defaults and includes stuff like pagekite and letsencrypt.