Investigations into the Starfield preload files reveal a distinct lack of Nvidia DLSS or Intel XeSS footprints, suggesting it will only support AMD FSR.
Only in visual quality is it miles better. Performance wise they're pretty close these days, with the slight edge to DLSS.
But all PC games moving forward should ship with FSR, DLSS, and XeSS to accommodate everyone. They shouldn't even be too hard to implement as Unreal Engine has made it as simple as a toggle to enable DLSS. Modders have also figured out their own ways as well. Because of that, just having only FSR looks like corporate greed.