Depends on what your DW manufacturer recommends. Mine is under the sink so the garbage disposal can also be plugged in to the same outlet.

The junction box only needs to be accessible. Which means you don't have to remove the finished surface of the building to get to it.

The question is whether you need a disconnect for this appliance. Most dishwashers I've seen are cord and plug connected under the sink, which is obviously more convenient, but pulling the dishwasher to get to the disconnect isn't a problem with most residential dishwashers. It's a royal pain however on some like the dual FP dishdrawers (which are abominations to begin with). Note that the breaker could serve as a disconnect as long as you can either see it while servicing the dishwasher or it is lockable.

Do you mean a junction box with a plate on it that an approved splice is concealed within? Or do you mean the actual outlet for the DW? Because the former is fine. But I personally want the DW disconnect under the sink where I doN’t have to yank it out to get to it when the pump burns up and is on fire.

Junction box with a plate where splice is concealed.

The dishwasher on fire, I'm heading to my breaker panel and shut it off there. The disconnect requirement is entirely to guard the maintenance person.

Some dishwasher installations actually have a switch for a disconnect, I'd look to see if you have a mystery switch under the sink (or otherwise near the dishwasher) and try that.

Maybe these definitions will help put it in perspective. For this situation, it would be the second definition for wiring methods.

It should be fine.