However, the other solution is the one you’ve already mentioned where you never plug the Smart TV into the internet, and instead bypass the “smart” on the TV with your own streaming boxes.
I did this for a long time on my old Vizio TV, but the experience was notably worse with external devices compared to built-in, due to the limited framerate support over HDMI. This led to awkward juddering when e.g. trying to play 23.976fps movies with only 30hz or 60hz output. It also meant built-in video features like motion interpolation did not work effectively.
I guess this is less of an issue today with VRR support on high-end TVs, but still, a lot of devices you might connect to a TV don’t support VRR.