There absolutely were pocket TV’s. As a kid, even, I owned two of them. They are now of course functionally useless because they predate the switch to digital television by a significant margin. Both of mine were Realistic brand ones, which was an in store label for Radio Shack. Color LCD displays, telescoping antenna, and they ran off of 4 AA batteries. They were about the size of an OG Gameboy or a large Walkman.
I might even still have one in a box of tech junk somewhere. I believe the second one was a Realistic Pocketvision 27.
You can still buy a portable digital TV. These were always a bit of a stretch for a “pocket” television, more the size of a small tablet but thicker. But they totally did, and still do, exist.