Sony seems to like to buy studios who they have a close relationship with (mostly). So Arrowhead (Helldivers 2) and Shift Up (Stellar Blade) make the most sense. Larian didn't have any kind of special relationship with Sony when releasing Baldurs Gate 3, PS5 is just what they chose to release (a month later mind you after the PC release) due to issues they were having with Xbox development. Although Larian makes sense from purely a WRPG perspective as Sony themselves have no studios producing them (and MS has been on a spree of buying WRPG developers Inxile, Obsidian, Bethesda, and Blizzard).
As far as Japanese devs, I'm not sure who they could target tbh. I've seen some publishers thrown around like Square Enix and Capcom but if Sony were going to target a publisher I think Konami would make more sense; considering their game development ability is basically nonexistent (and yes, I'm aware of the MGS remaster ports which honestly look like they're going to be hot garbage so even more of a reason Sony should target them as Konami clearly has lost all ability to actually make a video game).
Note: Just because I list a potential target by Sony doesn't mean I WANT Sony to go after them. I'm purely speculating on who Sony COULD go after
