Steam Controller is a flawed masterpiece that I wish we had gotten another iteration of.
Also, speaking of the 8bitdo Pro 2 line, the wired Xbox version of the Pro 2 is pretty great. It's similar to the regular Pro 2, but it has analog triggers, uses Xinput, and has Xbox coloring and branding. It's like they took the best parts of Xbox, SNES, and Playstation controllers and mushed them all together.
I've heard figures as high as 390 million. I'm pretty sure there are more guns than people in the US.