You could get an external digital tuners and a hdmi switch to switch between pc and the TV.

My country just disabled radio and tv over coax wire and provider send ip-TV boxes.
This allows to have now faster internet, which I like.

I would use an Apple TV or a Chromecast in that case. Most TV providers that I know offer their own mediabox anyway, so no need for TV Tuners anymore.

They do, but they much more expensive than a smart TV, even though they have less components.. Because a Smart TV is sold for less because its providing the vendor access to you as a product to all of their 3rd party partners.

I will add that you can also still get Westinghouse dumb TVs with included DVD player and USB video player, 3x HDMI and a tuner, but 1080p and Max 36"

It doesn't matter if you get one. They are the cheapest and best image quality TVs available, and many like Samsung's let you set them up without connecting to Wi-Fi.