The merchant/processor/issuer network with all the correct incentives is (nearly) impossible to replicate. Visa and Mastercard work more or less, perfectly.

The only entities that need/want "instant, non-recourse payments" are fraudsters.

In the EU countries with local instant bank payments schemes they are much more popular with consumers than credit cards when paying attrusted merchants, who in turn pay around a quarter in fees of what they'd have to pay for cards. No need for expensive credit cards schemes in Europe any more.