Trigger on general I/O ETA?

Contemplating adding external steppers to my Duet 2 Maestro for 3 point motorized bed leveling, but the stepper headers doesn't have end stop inputs associated with them, so it seems to me we would need support for trigger on GPIO to fully utilize the two extra stepper drivers?

Adding buttons to remaining inputs would also be very convenient, but while M581 P60 S0 T2 doesnt't say unsupported it also seems to not work, which is what the wiki suggests, so I guess it's all "are we there yet" until the future arrives:)

Stephen6309

@bearer You use a Z probe to do the bed leveling with three motors. https://duet3d.dozuki.com/Wiki/Bed_levelling_using_multiple_independent_Z_motors

I guess assumptions is the mother ... I just spent today playing with two z motors, and two limit switches to sync up Z axis, and assumed adding a 3rd would require a end stop.

Half the "problem" "solved"; still interested in hearing where on the to-do list general I/O triggers are though.
(Edit: Come to think of it, probably something that gets solved with v3 anyways (beta1 has no M581 support). Wait and see:)