US has more than 10,000 banks and credit unions. That combined with the fact that US the most "market driven" of the industrialized countries it has take a backseat approach of letting the "market" solve it
There have been attempts by the "market" e.g. wallets and lately "push to card" by VISA/MC and RTP by the The Clearing House but it has realized that the Federal Government needs to come up with a standard settlement network with specifications and a protocol that "market" i.e. private companies can build upon.
Given the timeline i.e. 2023-2024, it may be a little late since apps and companies building on top of P2C (Push to Card) and RTP (Real-time Payments ) are likely to corner substantial portion of faster 24x365 payments before FedNow is ready.
And don't forget even if it's ready on time it'll take another 2-4 years for all the Financial Institutions to connect to it