As I see it, the innovative part is that the service is push-only. With ACH and most other systems in the US, payees can pull from accounts, while FedNow has no support for forceful debits. That's a significant shift in the way we think about payments (for the better, IMHO). This has been done before by other service providers, but not by someone with this kind of influence and clout in the US.
Hmm, surely there's some kind of support for a pull request that has to be approved, no?
It seems like requiring the consumer to manually set up a push payment to a company would probably be annoying and error prone, compared to having them entering their details on a website and then the company requesting payment.
We already have a push system called Check 21. You scan an image of a check and it will send the money instantly to the bank instead of through the Fed. It created after 9/11, as money couldn't move when the Fed was frozen.