Alternative: If you've diced the tomatoes, you can blend the taco seasoning in with the tomatoes instead. This produces slightly different result, but is just as good.
Also, any brand of flatbread can be used - just make sure it's similar size or adjust amount of ingredients accordingly.
Commentary:
This simple "pizza" was inspired by 3 things: Quesadillas made with just cheese and diced chiles ... and sometimes diced fresh tomatoes have been a staple at our house for years. And I happened to have lots of fresh tomatoes and some absolutely wonderful flatbread (Stonefire Artisan Flatbread). But I wanted a bit more Southwestern kick, so we've got spices in this.
But if you're expecting a classic pizza with a Southwestern flavor - this isn't it. There's no sauce on this pizza so it's more like flatbread topped with cheese, chiles and tomatoes. More like the kind of quesadillas I love, but in pizza form. (BTW, I think I'm going to try a classic pizza made Southwestern next.)
I used mild green chiles in this. Personally, I prefer a medium hot like a Big Jim in this, but I was also serving this to someone who likes it really mild.