i don't think sayonara is an exclusive game at all, honestly. i'm thinking there'll be two kind of games on apple arcade:
a, the games where apple is directly involved and paid the devs for exclusivity (either apple approached the dev or the other way around), these will be exclusive to apple arcade for a while and then be allowed to come to pc/consoles.
b, premium games where the dev just wants to put them on apple arcade cuz the market for premium, non-f2p mobile game is super small now. that way they can make some money from thei mobile port, and put the game wherever else they want.