Wow so much to unpack here. Outside of the very first statement here, up to the ellipsis, this is just...incoherent.
Texas is not culturally "in the South," I agree with that. That's because Texas is culturally, well, Texas. Surely people here remember the ad campaign, "Texas...it's like a whole 'nother country?" That is possibly the truest statement about Texas, culturally, as there ever was. Texas, first and foremost, is ALL ABOUT SOME TEXAS.
Can you go to a roadside gas station in Evansville, Indiana, and find state-of-Indiana-themed stuff everywhere? Not that I've seen. Want to make Texas shaped pancakes? Got you. Want a freaking $10k BBQ grill shaped like Texas? Yassir. Want an in-ground pool shaped like Texas? Got it on special this week hoss. Ever see an Illinois-edition vehicle? There's a Texas Edition of just about every pickup truck AND full-size SUV - you can use it to tow your Texas-shaped grill to your house full of Texas Lone Star decor with your Texas-shaped pool in the backyard.
In a weird way, Texas is it's own avatar - a caricature of itself - and MANY residents embrace it so completely that it's just part of the fabric. Texas is not akin to the Mountain States, though some residents of El Paso likely sympathize with what's important in New Mexico - since New Mexico is closer than Austin. (Fun facts: El Paso is closer by mileage to California than it is to the Sabine River - Texas's eastern border. Port Arthur, TX is closer, mileage-wise, to Chicago than it is to El Paso.) Dallas sucks, IMO, but it is not culturally aligned with the midwest - try wearing jeans, a suit jacket, and a cowboy hat to an auto executive meeting in Detroit and tell me how that goes. West of a line between Tyler and Houston (which is only about a third of the state north to south) is San Antonio which has about as much in common with southern Illinois as ancho chile salsa on tacos has with ranch dressing on chicken tenders. Slow-smoked BBQ brisket (which is, you know, beef) is freaking fantastic.
Don’t let yourself get triggered over what some Deep South inbred fucks think of us. We are not a cultural match with most of the SEC and it would be a shame if we aspired to or if we stooped to trying to convince them we fit it. We don’t need to fit in. Who gives a shit.