The UPI over credit card is primarily there for peer-peee merchant transactions...
Nope. Signing up as a merchant is simply the matter of downloading the business version of GPay or Paytm and submitting minimal KYC documents.
> peer-peee merchant
Did not understand this part.
I think you were talking about registering as a peer-merchant, not a "proper" merchant! MDR etc cannot be charged on peer-merchants[1], and are essentially peers, but with restricted purpose codes that they can accept money for.
[1] https://www.npci.org.in/PDF/npci/upi/circular/2019/Circular%...
Of course, it is possible there might be some bank offering a pix-enabled credit card, but I don't see how they'd have any incentive, precisely because people could start doing that.