TCL roku TVs are cheap and you can just tell them you don't have an internet connection (or whatever) on first setup. I have no idea if TCL or Roku have pulled a samsung/sony/visio - i forget which - and connect to "open wifi" to phone home.

I got tired of my TCL Roku taking so long to turn on and switch inputs and turning itself on and off to update. So i factory reset it and told it "no network". works fine.

Sceptre makes dumb TVs, too. https://www.sceptre.com/ - i have been buying their panels for something like 24 years. they're "decent" nothing super remarkable, but they're just dumb displays. at least mine are.

And finally, find a projector that does what you want. they're usually so compact they don't have roku/other smart stuff. I use a wall, we used dark brown or black paint to frame out a 95" screen roughly in between 16:8 and 16:9 aspect. wash the wall or sand lightly and wash the wall, then apply Behr Silver Screen in the matte-est behr base. I personally did three coats, it took less than a quart, so you only need a quart for ~100" with 3 coats. It looks like a movie screen when it's off, and it looks like a TV screen when the projector is on.

observe a random clip of it in action https://www.youtube.com/watch?v=YG6VJ9WlLcs note i know there is trapezoid, i fixed that later by ceiling mounting the projector in the middle as opposed to slightly to the side. a more expensive / nicer projector can actually transform the image trapezoid to fix this, and the most expensive can do it on their own! mine has vertical trap but not horizontal.

pitch black room and vibrant colors (powanqatsi maybe) https://www.youtube.com/watch?v=vYrsm2B9UeY