Thank you, Chefs!
As usual, I was not understanding what was being said.
Last July I did a prime rib in my BIL's gas grill without smoke, but I did put a pan underneath it with a mirepoix that caught the juices. I strained the pan to get the juices and poured off the fat then blended a bit of the soft veg in a blender and poured the juice into it. This was my au jus dip. I got great reviews but I'm sure the people I served would have said nice things even if it had been a disaster.
I didn't feel like it was a waste of time, but I'm not a pro.
BTW: I also made a horseradish sauce for dipping.
Thank you, again, for the responses.
rh