I don't think the hardware is the issue. Having their service on PlayStation isn't going to sell anyone an XBox.
I think third party games is the issue for Sony. They let EA do their own games in a subscription. They don't have the more expensive full version that includes third party games (though it could be their cut being EA not wanting to sell it instead).
For Nintendo, regardless of ideology (where they probably object just to object), I think if they started work right now, we'd see their store being capable of gamepass in a decade or so.
Having their service on PlayStation isn’t going to sell anyone an XBox.
Sure it would. If PlayStation got only fewer games and/or less optimized versions of those games, it would be nothing but promoting a closed competing platform that would never allow PlayStation Plus onto its platform.
Sony is basically doing something similar with their Windows ports of PlayStation games. The ports of God of War and Horizon Zero Dawn were released under a year before the originally planned release dates of the sequels.