Depends on your definition of "quite pricey." There's no equivalent of a $250 50" Insignia FireTV, but I've seen Samsung signage displays on Amazon for about a $75-$100 premium over their comparable Smart TVs. They also don't come with a stand, so if you weren't already buying a VESA mount you'll need to add another $40-80. There is a significant premium, but it's not necessarily orders of magnitude.
Apparently "smartness" has not invaded projectors...per a comment I read here on kbin a while back from a projector owner. This really encourages me to buy one.
They're harder to find, for sure. Especially if you want a large screen.
When I was shopping around a few years ago, the only 65" TV I could find without smart features was a Sceptre, which is Walmart's electronics brand. Speakers so bad that I had to buy a sound bar, and the display isn't that great, but it gets the job done and I don't need to worry about it being an attack vector.
Yepp - hop on Ebay or some surplus auction site, and search for commercial/signage displays. Don't bother buying new unless you have the money for it IMO, they are expensive unless you get them used
Not really but you can always get a "smart" tv and never connect it to the Internet. If you want to stream just use an external device you trust like a PC