For starters…PCs (at least when it comes to Windows) and Xbox Series X are apart of the same ecosystem…one that Microsoft is looking to bring closer together with these moves.
Microsoft wants gamers…period. Rather thats Series X or Windows 10, they will happily accept you as equals either way. However, at least for the first year or two, SX will have an advantage in key areas until PC gamers make it viable for devs to use some of these technologies on that platform. PC will still have the advantage in raw graphical fidelity, but SX will cost just a fraction of the price compared to rigs in its class.