Unfortunately the family likes live TV, and that is very hard to get without compromising the UX.
It's been a bit since I've done this (I'm not watching live TV anymore), but something like HDHomeRun worked fine.
It basically pairs an antenna with a small computer to convert to network traffic, then gives you an app on your streaming device to play it back.
You do need to be able to run the vendor's app, and you'll get stuck with that UI for live tv (So yeah - totally agree that you're compromising the UX). But still no reliance on the "smarts" built into the tv.
You're right, though - both Plex and Jellyfin seem to have pretty good support these days, so if you're already running one of those it's a nicer integration.