Sure, GF alternatives exist, but the question is specifically finding a good one at a local restaurant. Most places have corn and flour and that's it.

My wife has Celiacs, and we've unfortunately never seen a GF burrito in the wild. However, the existence of those GF burrito tortillas is duly noted and I'm excited to test them out.

Authentic Mexican restaurants are almost always celiac-friendly, EXCEPT for burritos (and quesadillas). Corn tortillas just don't hold up well once they get that wide, it's a matter of practicality.

For reference, Mission's "Super Size" corn tortillas are less than six inches in diameter. You need at least 10-12 for a burrito that deserves the name.