Just disconnect it from your network (change the wifi password or remove the Ethernet cable) and it will be unable to auto-update.
You may want to get an external device (Roku, Chromecast, Apple TV, or other media server) and plug that into your HDMI if you use the network from apps on the TV.
Just wait 'til they get a blanket connection to Amazon Sidewalk for their nefarious deeds, and the only way to disable it will involve a soldering iron.
What can the apps on your TV do that a $40 Amazon Fire stick ($50 if you want 4K) can't?
I'd rather hook up an old laptop to my TV and use that to watch media than use the apps on my TV and deal with all the bullshit that TV manufacturers are doing when you connect the TV to the network.