How do users choose /ApplePay/Google Pay/etc?

PayPal is not available with the Stripe Add-On.

For Google Pay, if you’ve configured Stripe correctly, they will only see that option if they are on a Chrome Browser. Likewise, for Apple Pay, they must be on a Safari browser (or iPhone/iPad).

If those options are not showing, you would need to open a Support Ticket to see what the issue may be.