Dallas is a liberal stronghold in Texas, and in absolute numbers turns out more for Democrats than any other city in the state, including Austin (percentage-wise Austin wins by +5%, I believe). Unlike Austin, which is gerrymandered in the state legislature, every single state/county/city official in Dallas is a Democrat.
Dallas is also a gay rights stronghold, representing the only county and city in Texas, again including Austin, with non-discrimination clauses in employment and housing for LGBTQ+ individuals.
Furthermore— Texas is considering bi-partisan legislation to legalize weed. Dallas has already decriminalized it, and the State, while backwards in other regards, hasn’t indicated it will force Dallas to back down on that measure. Dallas also has stricter gun laws than the state of Texas.
Texas has a long way to go, but I think if you would step in Dallas you would learn to leave your preconceived notions of it at the door.
I believe an HQ2 would speed up Texas’ change.