Few banks support consumer-initiated FedNow transfers. The main near-term application is receiving government payments: Medicare, tax refunds, and such. The US Treasury wants to convert over, to reduce customer service issues. ("Where's my Social Security check?") If it only takes seconds, customer service and actual money transfer are in sync.

Banks are dragging their feet on customer-initiated transfers because of the fraud problem. If you send money by FedNow, it's gone. So there's a lot of scam potential. Wells Fargo supports bill pay via FedNow to known payees, which is useful. Pay a bill, and the payee gets paid immediately. Both sides can see the transaction as completed. That's useful.

The ability to send your entire bank account to anybody in seconds with no way to reverse the transaction is rather risky.