[MadnessASAP]

You'd use X for L to L/N, Y is for N to Ground. Those isolated power supplies are definitley grounded, definitely not what Apple is using, and will probably shut themselves off if they lose their ground connection (or at least signal a fault to the operator)

[grues-dinner]

Unlikely, since you can quite happily buy two-prong power supplies.

And most packaged modules don't even have ground connections, e.g. https://www.tracopower.com/sites/default/files/products/data...

You're also confusing the Y designation, which relates to the capacitor properties, to the application. Not all Y capacitors are used for line-to-ground applications. However any application where a failure to a closed state would result in a shock hazard must use Y-rated capacitors.