Why leave out Pebble? Because it's well over a million by now? Plus bear in mind that Android Wear only started middle of 2014, and didn't really get hot until the Moto 360 and LG R came out in September.
In any case, okay, let's just do Wear and Gear to date:
1.2 million ... Android watches sold in
2013 (probably most Samsung Gear)
+
2.0 million ... Samsung Gear watches sold in 2014
0.7 million ... Android Wear watches sold in the last part of 2014
========================
3.9 million ... total for 2013-14
Without even accelerating sales (which are expected to double each year), we can lowball add another 1.4 million sold through the end of May 2015.
So, at least 5.0 - 5.3 million Gear and Wear sold to date. Could easily be more like 6 - 8 million in reality.
Yes, it took a couple of years, but the market has been doubling each year. That's why Apple decided to jump in.
This is not meant in any way to negate Apple's success. It's just to keep some comparisons realistic.