I'm thinking Japanese people are buying these to play on the go, but I still haven't seen a single person playing a Switch outside. (nor being sold in a shop)
As I said earlier in the thread, I've just got back from 2 weeks in Japan with my son and he and I were the only 2 people using a 3DS or Switch that I saw the whole time I was there. We took various modes of transport from Shinkansen to local trains to subways and I didn't see a single person with either device. Literally everybody was on their phones. So I'm not completely buying that the portable aspect is a huge selling point in Japan and I'm guessing it may be more the small form factor for a home console that appeals.