Seat belts blow when airbags go off. Theres basically a small explosive charge that locks them in place. So for that, you'll need the curtain airbags, headliner, belt retractor, and buckle, airbag module (which will need to be programmed via Tech II). Front end doesn't look bad at all. I highly doubt there's any damage to the frame (maybe a bent horn, but that's an easy fix. Definitely not a total, but glad to hear you're not hurt.
You have one of the best looking Avalanches Ive seen. Get it back together and back on the road!
Bring it to Houston and Ill fix it myself!