Jan 26 announcement of pilot program:

Announcing the FedNow Pilot Program participants (frbservices.org)

February 24 announcement of strategic approach to using ISO20022:

Our strategic approach to the FedNow Service ISO 20022 message specifications (frbservices.org)

Historically, the Fed stands up a pilot program partly to prove the design, efficiency, and functionality of a new or improved Fed service and partly to use a limited rollout before scaling up a new or improved service for general availability.  In the case of FedNow, the pilot probably leans more toward the former use case, proving up the core functionalities, refining design, and looking for hiccups before committing to a final design and a final rule set for general availability by 2023.

When the Fed publishes its promised FedNow “rulebook” (likely I the form of a new FedNow specific operating circular to join OC3 for check services, OC4 for FedACH, and OC6 for FedWire), P to FedNow users I&R will provide analysis of what’s in the new rulebook and, just as importantly, what gaps the Fed leavies to be filled in by agreements between FedNow ser institutions, payment processors and other non bank service providers, and the end users of the Fed’s instant payment solution.