Earlier quoted context omitted.
Can't you just remove the smart TV's internet access (no wifi pw, no Ethernet) and treat it as dumb? Then attach a Chromecast or whatever "smart" dongle you think has the best UI.
This is definitely one approach, but I would actually just prefer a full computer, because I do sometimes run other software that is simply not available on any dongles. One downside though is that I only have a couple HDMI ports to work with, so between a Nintendo Switch and a full desktop PC I'm already using all of the ports. Also, even though I love the NVIDIA Shield, I find it does not really integrate as well a…
Typically you'd buy a receiver to take all the HDMI inputs and power speakers and control which source went to the TV via a single HDMI cord. My receiver has something like 6 HDMI ports. Smart TVs have attempted to invert this relationship by accepting HDMI and splitting audio out to the receiver, but you don't have to play along.