2 million is the "platinum" number, but my understanding is it only applies to sales. At least from what I've read in the past, albums that are given away are not eligible for those certifications.
The number though, is the ones who got it through the iTunes store. That would be the people who don't own iOS devices, and had to specifically seek it out, wouldn't it?
I'd much rather see Apple move to the head of the display tech industry instead of always following so far behind. Ultra-wide, IMO, is much more impressive and versatile than 4k. Look at the LG 34UM95, now THAT is an impressive monitor. If Apple could bring us a 4K Ultra-wide??? Now that would make Apple a leader!