Does anyone still make good "dumb" TVs that don't want/need an internet connection?
No. Ad revenue offsets the cost of TVs. That's why they've become so cheap. Very few people would pay the extra cash for TVs without it so they don't manufacture them.
Easy solution: buy an external whatever and never connect it to the internet. HDMI-CEC means it will turn on and auto switch the input to whatever device turned on.
These also tends to be designed for 16/7 runtime, which should be way more than most residential usage — unless grandma keeps it running 24/7… but hey, if you splurge a bit more, there are models designed for 24/7 as well.
I bought a 50" TCL 5 Series a few years ago on-sale and never connected it to internet. It does fine for my needs and doesn't bother me about connection or apps at all.