On paper the FF XVI drop looks normal, it's in line with previous entries. But previous entries also did at least 2x the debut, and that includes FF XV. When FF XV launched, PS4 install base in Japan (and globally) was about the same as PS5's.
So I wouldn't say XVI's performance has been great in Japan, but the game does seem to have more appeal in Western markets. I'm expecting US to be the biggest market for XVI sales by far, for example. I also thought that maybe XVI would have a long-term effect on boosting PS5 hardware & software numbers in Japan but, that doesn't seem to be happening, either.
I think it's okay to say FF XVI and PS5 itself have done well in Japan, but they could definitely be doing better. I just don't know how much PS5 in its current form can actually do in Japan without some sort of (real) portable option, and Project Q ain't it.
Maybe a PS5 laptop-like portable? That should easily be doable engineering-wise. I don't think a high-ish price would necessarily be a barrier either.
Globally that means really good things, but this link you give is specifically for the US market. It's of no correlation to how the game is selling in Japan, sadly.
I'm expecting the US to be the #1 region for the game's sales by far, followed by UK & Europe.
The PS5 install base is definitely smaller In Japan launched aligned with PS4. A lot of PS5's didn't stay in Japan