Oh yeah, you want dumb everything else beyond the little box that you control which has the “smarts” and something like Linux and Kodi on it.
Even having Windows on that box would pretty much guarantee you have no privacy.
As it so happens, in my experience of over a decade using Media Players to play videos on my TV (since well before Android TV and Smart TVs) it’s even the most economic option: the life-cycle of the hardware that plays videos is a lot tighter than the life-cycle of the actual display - unless you’re running after the bleeding edge, you more often have to replace the video playing hardware because it doesn’t support newer video codecs than then display - so it’s cheaper to have those things be separate so that you don’t have to replaced the whole thing every few years just because the cheaper part - the processor - can’t decode newer codecs and instead can just replace the “smarts” and not spend any money on the stuff that still works fine (and is actually more expensive).
Further, if one does like I do and actually use that box for more things (my Media Player Mini-PC is also a home server and home NAS), that’s yet another way that such a setup ends up being cheaper because it’s being used to do the work of 2 or 3 things.
I suspect even if one pays twice as much for a non-smart “Hospitality Display” to have alongside your own self-made Media Player box, it’ll still end up cheaper because in 5-10 years’ time that display will still be just fine even while that box might need upgrading due to new video codecs.