I think the "Japan only cares about handhelds/mobile" stuff is brought up too often and is rather diversionary.
It's not like PS hasn't done well in Japan before after all, plus the Switch Lite is the worst selling Switch variant too, and by a long shot.
Yes, they do not only care about handelds, and the same way the handheld factor is crucial and not something to downplay as a side effect of the console. (which i find weird to this day, as if mentioning the hybrid factor is somehow donwplaying Nintendo's success - no it's not, they made a fantastic hardware)
the fact that you have a hybrid console, so that you can choose to play at home while also taking your console outside is huge ! you have a choice - so of course it's more attractive to a home console that you can only use at home.
That Switch Lite comparison would make sense if there was another version of a switch, that you can only use as home console. Other than that, a hybrid variant is obviously more attractive
Splatoon sold a million on the Wii U. Ring Fit has sold over 3 million. You don't need to be playable on a commute to succeed in Japan. Portability didn't prevent the Vita doing way worse than PS3 or PS4.
It would be like claiming that the reason the 3DS did poorly in Europe was this it wasn't a home console. Software is far far more important than form factor.
and how did those games help the wii U ?
like i said - you need the right hardaware and the right software.
What Nintendo lacked with the Wii U (Hardware not Software) is now gone with the Switch (the perfect symbiose of great hardware and software).
And that is something that Sony can not cover just with software
