Source: https://bsky.app/profile/funnysnarkyjoke.bsky.social/post/3lmkfwebeuc27
In fact you can use your smartphone to change the channel on nearly any TV. In the comments on that post some people talk about how to do it. Basically you need a smartphone with either builtin IR or use a USB-C IR blaster or if your phone has a 3.5mm headphone jack you can also try one of those but I’m not sure if the 3.5mm ones are as commonly supported.
So you could make your own by buying 3.5mm jacks and wiring a 2-4 ohm resistor (whatever standard headphone resistance is) in it to simulate the headphone, then just plug it in. Kindof a bother I guess to make, carry, and then obviously hunt around the back of a tv to install one, but it certainly could be done.