Maybe, maybe not, but they can build it on a state border.
Well that is their state border so I guess it all comes down to whatever deal was made when TX became a state. I think there’s at least one city right against the border. San Antonio? Is part if that city on federal border easement? Is there such a thing as a federal border easement? I know fedgov owns a lot of border land further West that the dept of BLM oversees.
If they became the Republic of Texas again they damn well could...on THEIR national border.