Transfers within Venmo fake immediacy. If it depends on an ACH transfer (ie the money is coming from a bank account and not an existing Venmo balance) then the money will be taken back if the ACH fails.
It's transfers between Venmo and a bank that would get faster.
There‘s nothing fake about a bank or payment service provider giving you access to unsettled funds if they can be reasonably sure that they will ultimately be made whole.
Banks are required to make the first $200 or so of a deposited check available immediately, and at that point it‘s not even clear if the check will clear, much less has the money already settled.
What‘s important to have in real time is a payment guarantee, but of course it helps the receiving institution with liquidity management if the settlement itself is also instantaneous.
There are stories of Venmo transfers that do not include ACH (ie the source of funds is a venmo balance) being difficult or impossible to reverse. That's purely a product choice by Paypal.
It's transfers between Venmo and a bank that would get faster.