Honestly, the biggest thing holding back Sony ports to Xbox is probably Microsoft's insistence on platform support for the Series S.

I don’t agree with that assessment given Sony only published games on the Xbox One when forced to by the license holder. They also seem to do just fine porting their games to PC where there is a host of different hardware configurations. Go look at the minimum PC specs for Ratchet and Clank; that sure seems like it could run on a Series S to me.