If you go to a BBQ place in the southeast it's very likely to have Brunswick stew as a side, along with fries, slaw, rings ... I infer that stops being likely west of the Mississippi, and maybe even 100 miles or more east of that. They didn't have it in Cincy very often at places, so maybe into TN you don't see it much.
Fox Bros here has it, and it's good, I think, and the Bros. are Texans. That is my "go to place", though I read about some other spots I've yet to try here. One thing to avoid of course is going to a "Chilis" and seeing BBQ on the menu. Don't. The bor/restaurant next to us has BBQ on the menu, it's edible, I tried it. But not good. I think they buy it from "Kroger", or Sysco, already done. They do some things well, usually fried things, like Totchos (which they claim to have invented).
The other regional thing here that is popular is shrimp and grits, which most places serve for brunch. It's literally grits, with some shrimp in it, and maybe some cheese whatever. It's OK to me, but they can charge $20 for it, basically grits which are about as low cost as a thing can be, and four shrimp. The other thing is chicken and waffles, which I also don't "get". The chicken can be pretty good, fried of course, fine, but with waffles?
Folks apparently sit around drinking and pondering "What can we serve as some weird combination that is cheap and charge $20 for?".
Buffalo wings has a similar kind of story.