Any way to *legally* watch home games on mobile devices?

It still baffles me that the Astros and MLB are stuck in 20th-century blackout mindset. I am already paying for ATT Sports Southwest to have the games on my XFinity cable subscription, but, if it's a home game, the mobile app for XFinity will black out the games.

Is there any equivalent to an old-school SlingBox that would just show my live cable remotely? Now that sling has gone into their own streaming service, I don't think that's possible?

Is there any way to do this legally that doesn't break the bank?