I have a short season, but have successfully grew hundreds of varieties of peppers. The critical thing is to start the seeds indoors here 90-120 days before planting outdoors. I don't have a greenhouse. I grow under cheap fluorescent lights just for vegetative growth. My outdoor season is from early June to mid-October most years. I never have tried to grow Piper Nigrum. I may try sometime.
Regarding spiciest, Mexican ones are hot, but they aren't even close heatwise to some of the nuclear hot ones in India, Bangladesh, Trinidad, and even a few I've heard of in Pakistan.

I am interested in learning what some of the more 'common' popular types are in Pakistan. I enjoy learning more about landrace varieties in different regions.