Hardware/software-wise, yes, but putting money on the card is a problem if you don't have a credit/debit card issued by a Japanese bank (or perhaps a few others). That's fine for locals, of course, but not helpful for many foreign visitors.
I had no problem topping it up with apple pay while in Japan.
Correct. No Japanese CC needed.
Yes but I'm not going to buy a phone with an OS that I dislike just for my occasional trips to Japan.