My credit unions now offer ach, same day ach, and instant transfers between them.

Same day ach launched with a user fee, so they usually prompt to confirm and offer to send it via normal ach instead, which I find amusing?

I also see instant transfer support at some other places I bank. I can't say if bill payment happens instantly or not, my finances don't run close to the edge, and I don't need to know exactly when a bill pay (which I generally schedule) is taken out and when it's applied; as long as both happen, I'm good.