Transferring money using Zelle [0], between participating banks, is pretty much instantly, at least in my experience. The limit is up to 20,000 monthly for me. YMMV.
Might not be people's first choice, but Facebook is instant. Like, the money is a non pending deposit seconds after the sender clicks send. Slick, and not a silly extra checking account like venmo.
there are a couple tiers of paid wire transfers, but still no guarantees that you will have liquid settled cash in the same business day.
the mere concept of the SEPA system in the EU is pretty nice