I would create a second (if need be) Drill toolpath which starts just above the bottom of the hole and then plunges a tiny distance at a suitable slow speed so as to cause the dwell effect.
and see if there’s a hook into the Drill toolpath to allow adding the Dwell and use that post-processor.
Or write a custom tool to make the G-code.
If you could provide an example set of feeds and speeds and Dwell times and height/depths and stock size and toolpath positions we could look into this with you.