Venmo, PayPal, and Zelle are all consumer-facing products. FedNow is a service for interbank settlement only, not a consumer product. FedNow does create an opportunity for banks to provide instant payments for their customers, but that just means banks (even small banks) will be able to compete well with Venmo and others. That seems like a win for everyone to me.
Adding onto this, the Fed has proposed opening up Fed Master Accounts to non-bank fintechs (e.g., PayPal/Venmo). That would allow them to improve their own services by moving off of ACH.
For those interested in the Fed Master Accounts topic, I recommend this Macro Musings podcast episode with George Selgin.[1]