First off, why on earth would you want to relocate from Texas to MD/VA? Hoping it's because your wife must relocate for work and she is the primary bread winner, because otherwise I would tell you that your crazy man haha. For the most part to get a 911 job in the area you are going to have to apply with the Fire Services and about 95% of them want you to be dual certified and will put you through a fire academy. Washington D.C. has civilian paramedics which do not have to do fire side, but they are one of the worst EMS systems in the nation IMO and the benefits suck compared to their union brother firefighters. The ONLY place that I would encourage you to look into if looking for EMS only and a great department would be Arlington County VA. Their FD hires Paramedics for EMS only, however it's extremely competative to get hired there and the written test is no joke. Heavy in chemistry and math.
Any MD department worth working for is going to be dual role.
If I were you and you are set on moving here, I would bite the bullet and apply to places like Fairfax, Arlington, Loudon, Alexandria, which are all Northern VA departments. Do the academy and learn the fire stuff, and if you only wanna ride a medic unit trust me they will make that happen. There are plenty of fire guys that will swap out with you as much as you would like. Going through the academy for dual role will allow you much more vertical movement for promotions etc. All of those departments are young, progressive, and squared away departments that have money, nice equipment, good protocols, etc. Pay, benefits, pension, etc all goes to the northern VA departments. MD is a ****ty state to live in. High taxes, extremely high cost of living, crappy gun laws, high crime, crappy schools, need I say more. Northern VA will be pricey as well, but those departments pay enough to make a living in those area's. If you need more info feel free to shoot me a PM.