cell phones work up there?

Yes, cell phones work there, but very dependent on your service. On the way up. Most providers and cell singles are bad/weak. So be prepared.

Google Fi works

On the way there it's not the best and it's also not the best at the mountain

I have T-MOBILE phone. Near the road side works well. But if you hike to mountain signal was very weak.

TMobile was okay, but my friend's AT&T was terrible

Verizon worked while I was there