I have a single Raspberry Pi 3b as a local file/media server running Jellyfin. I’m also running BOINC and seeding torrents of various Linux distributions. External HDD for storage, plus a thumb drive for the local media and another for the torrents so it only has to spin up when someone’s actually using it.

It’s not super-fast by any means, but it’s fast enough to listen to music over my LAN, which is the main thing I need it to do quickly. Though eventually I plan on setting up a better NAS on something with faster I/O.

If I was only using it for file sync, maybe. Though as it happens, the Linux desktop file sync client works fine on here, and I can work on files locally.

But that doesn’t help for things like, say, account settings, or tasks, or getting the right caldav URL to be able to plug it into a local client.

I’m using it for multiple services, not just one, and while some have apps available, not all do, and some features aren’t supported in the corresponding app.

I’m using Nextcloud for a lot more than just file sharing. Calendar, contacts, tasks, RSS reader sync, etc.

Same. Thunderbird now has native support for CalDAV and I use DAVx5 to sync it with my Android devices.