Thanks for mentioning VacuumTube, it sounds useful.

I’m using a Minix Z100 running Gnome and Kodi. I use a simple Bluetooth keyboard, the interface is clunky but it does the job. I use Samba to also share files to VNC running on iOS and Android on the same network.

I tried using fancier solutions but anything that browses content without involving directories always break for some specific content in unpredictable ways.

That has been my experience as well. So far nothing has come close to the flexibility of Gnome (upscaled) with an airmouse. I am keeping an eye on the Plasma Bigscreen project however (10-foot UI for Plasma).

An alternative could be some x86 Android TV build like Lineage, but I have not seen very convincing demonstrations that this is truly viable.