I actually think Bosch might be from Nayshall. A few months ago I speculated that Bosch "seemingly represents a pan-Asian culture that doesn't actually exist, similar to movies like Raya and the Last Dragon," and now we know that the game actually features such a location. His aesthetic even fits JP's stage. Maybe Bosch succumbs to JP's influence in his quest to surpass his rival (your avatar).
Edit: I missed this before, but a sign advertising a bank in the Old Town Market stage says "
Nayshall Branch," and the woman in the background is wearing clothing with a pattern very similar to the one on Bosch's bangle.