If you don't mind spending a bit of money, then I'd recommend an HW30 in .177 with a low powered scope. The .177 pellets lose energy very quickly, so they're unlikely to cause any damage if they fall back to earth, which is something you've got to take into account if you're shooting up into trees at squirrels in a neighborhood. You should make every effort you can to make sure you've got a safe backstop, but when you're shooting into trees things sometimes happen. I've had pellets bounce off of tree limbs and end up behind me before.
If you're looking to save money, then you might consider one of the Gamo's. They're not great, but for most people they're more than adequate and their price is reasonable. You don't need extreme power. What really counts is shot placement. Head, neck and heart lung area shots are the only ones you want to take and if you hit them in those areas a lower powered airgun will be fine.
A rifle is going to be significantly better than a pistol and I'd recommend choosing something that anyone can recognize as an airgun. Even in Texas, I'm sure there are a lot of Karen's that are just looking for something to be upset about.
If it's got to be an air pistol, then maybe I'd recommend a Diana Chaser in .22. I know I just finished recommending .177 and saying power doesn't matter, but that's only true of rifles. With inexpensive air pistols you need every bit of power you can get and you need good shot placement too and .22 hits a bit harder than .177. A scope will help with that shot placement.