I have used pork stew meat (great time saver!), pork loin, thick chops. You could even substitute chicken.
I use NM red chile powder, but you can use any good chile powder such as ancho, chipotle, guajillo, or a chile powder mix.
There really is no substitute for Hatch green chile. It is commercially available in cans and the freezer section of most of the U.S. now. In New Mexico, we freeze fresh chile in September to last through the year...
Slow-cookers vary in temperature. I set mine to "high" and cooked it for 6 hours. I'd say you could cook it 8 to 10 hours on low, and get good results.
In the Instant Pot, I use manual and set to high pressure for 45 minutes, then de-pressurize for 10 minutes before opening.
Macronutrients (approximation from MyFitnessPal.com): 338 calories; 41 g protein; 15 g fat; 6 g carbohydrates.