I think 10M is an unrealistic expectation for something that's been out what, 4 months?
ps4 pro and X1X have 20% sell rate compared to their base consoles, and while Lite is cheaper than switch it does not Switch so some buyers will never be able to get past that. Saying that, 26% (japan) to 40% (America) is pretty damn good imo.
Yes, but there's a lot of people that see Nintendo as a handheld company. Even when the Wii U faltered the 3DS was selling quite well. So having a device you could declare as the new Nintendo handheld is a big selling point.
Apparently most of the sales have been going to buying a second Switch for their SO/kids/whatever (which is the case in my case, wife wanted a second device for Pokemon) so it's good that it isn't taking a bite out of the sales of the OG Switch.