ACH involves the Federal Reserve Bank in every transfer. FedNow involves the Federal Reserve Bank in every transfer.

To be fair only about half of US ACH traffic flows through the Fed (the other half goes through the Clearing House Payments Company), but the Fed is very much involved (and a critical component of) the ACH network, even if the system is not explicitly a government one.

Nacha governs the ACH network and does not operate anything. The actual processing is split between the Fed and a company called Clearing House.