They're going to become PayPal. There's no scenario where that doesn't happen as they get larger and larger and larger. Especially as competition is eliminated.

On the consumer facing side Paypal is something I use when paying, but AFAIK I can't use Stripe (yet?). Stripe is used by businesses to let me pay with a credit card (or Paypal, Google Pay, etc etc).

Stripe link is a white label checkout page like what you're talking about. I believed all of shop pay also goes through stripe

Stripe Link is their answer to “using Stripe on the customer facing side”.