When you have multiple TVs in the house and you start to pair them with smart TV boxes, keeping track of it all can be a nightmare. Universal TV remotes used to be more popular when you just needed an IR transmitter and TV interfaces were simple, but these days, interfaces are more complex, and there's more to consider.
The solution is quite simple, though. An old Android tablet I don't use anymore quickly became everything I needed to control my TVs with next to gaps in functionality. And I wouldn't have it any other way.
You don't need an IR transmitter
TVs are all internet-connected now
In the past, for your phone to be a universal TV remote, you'd need it to be one of the rare examples of a phone with a built-in IR transmitter. These days, though, the majority of TVs can connect to the internet, and you can use any phone to control them.
You can find multiple universal remote control apps on your favorite app store that let you take advantage of this capability and control all the TVs in your home relatively easily. I found this particular app from BoostVision to be the most functional on a tablet. A lot of these apps also seem to be designed for smaller phone screens, but this one adjusts pretty well to the larger tablet display.
With my LG TV, I can use D-pad controls or a virtual touchpad to move the on-screen pointer, but I also get volume buttons, quick navigation…