Man this is depressing... I reached out to my salesman. I played dumb and acted like I didn't have any of this information already and asked why my order still doesn't have a build date. He wrote back and said because it has a diesel those are hard to come by and that's likely the issue. He didn't dig further and see that my order has max tow so that is more of a hold-up than the diesel, but he's in sales and I'll give him the benefit of the doubt that he doesn't have the constraint list sitting in front of him.
All that said, at this point I'm just going to keep an eye on the inventory of Suburbans/Yukon XLs and if something pops up that checks all or most of our boxes I'm going to make a call. Knowing what I know now I should have done that back when I placed my order in March, but little did I know this situation would continue to erode throughout 2022 and have no real end in sight.