Zelle is owned by a private company, owned by the US' largest banks [1]. The US Federal Reserve is working on a replacement [2] (FedNow) that presumably will have less power to keep banking entities (small banks, community banks) in the US with less pull off the network (with pricing or other mechanisms).

From the perspective that instant payments should be an inexpensive, accessible utility for the benefit of all citizens, the Fed's FedNow efforts are preferable to Zelle or legacy ACH services.

[1] https://en.wikipedia.org/wiki/Zelle_(payment_service)

[2] https://corpgov.law.harvard.edu/2020/08/31/fednow-the-federa...

I understand how Zelle pull off real-time for intrabank. For interbank, they are either covering it or have they built a payment service under the covers?

The final real reconciliation for Zelle is done over ACH.