You can absolutely find these, usually offered as commercial products, e.g. for menus, or billboards in airports, etc.
Buddy of mine used to work in a kabab shop before finishing his IT degree and helped out there off and on. He ordered an installed some 48" monitors (simple HD TVs) and then ordered a few for himself. I think they could 2 inputs max, but that's fine for most purposes.
Ads no longer work online, period. The ad industry is just 10 years behind acknowledging it. Most of what people pay for is just paying for the organic traffic you'd normally get with no ads so they don't give it to someone else. It's more of a protection racket than it is a source of genuine new customers.
I have rather different experience. Most people either don't care or don't know how to. Unless you're tech savvy you're watching ads. And if you're on mobile you're watching them anyway in many cases.
