Interrupt support comes via protected objects. Of course, you don’t need tasks other than the main program, and you don’t have to wait on the PO for the interrupt to happen; you can just poll it.
The containers needed quite a lot of editing, because the RTS doesn’t support finalization or exception propagation, and I haven’t looked at the latest code. Basically, they’re at the Ada2005 state; I’m pretty sure they support generalized iteration - yes, they do.