I’m not sure if they all do, but some models also support a daughter board for additional IO. Often it’s DisplayPort but I’ve seen ones with Ethernet and DB9/RS232 on AliExpress/ebay

Some of the HP DeskMini machines might be a good one. There’s a model that has 2 x m.2 for a little high speed network storage or as a HTPC.

Jellyfin has a remote control feature that lets you do something like this, I use it quite a lot for music.