Wait let me get this right, I might have completely misunderstood:
So you want to buy something and at check-out you let someone else pay with their credit card. You find that someone with WoT (and presumably use Nostr for this).
Discussion
I want to buy something online that can only be paid by card but don't have a card or don't want to dox myself. I go to this market and ask someone trustworthy to pay it for me (somehow) and I settle with them in sats. Trust is important because chargeback risk (though it depends on the product/service)
This is what gift cards and services like bitrefil aim to provide. Making it a marketplace is a fraud nightmare that will drive your operational costs to the moon.