Finally got access to the Telegram wallet which they announced last year but I'd never seen in the wild. 

Looks absolutely sick, but unfortunately nerfed if you're American due to anti-US rage from Pavel. 

What I can't figure out is how the app is figuring that out given I'm in Dubai, and region set to Spain/Europe.

In theory the app could be using the model numbers (which maps to the destination market), but not sure you can pull that in iOS. 

Also, a colleague who bought their iPhone in NYC is using the TG wallet fine while living in Mexico. So can't be that. Maybe time-averaging GPS location?

Some fine company the US is keeping these days.