You can't find what you want in stock somewhere? With the internet searches, you can pretty much search inventory of dealers across the country. I just mention that because when you read some of the offers from Stellantis (and other manufacturers also), they typically are focused on what is in the dealer stock, not special orders to the factory. In fact, that is why they usually offer rebates or financing deals because they want to move the inventory off the lots.
I have done it both ways when purchasing new vehicles but if you are somewhat flexible, you can usually get much better deals on in-stock units.
Daniel and Renee at Gupton Motors in Springfield, TN are awesome to work with. I purchased from them in 2021 and it was the most painless car buying process I've ever had.
I want the new Joose orange which is hard to find right now—plus I’d like to build it with specific options. I did that back 2019 when they rolled out and was able to find a dealer that would work with me. I hear you on the rebates mainly being on current stock—I may be out of luck finding a deal.
The ones in the spreadsheet I linked do deals on orders (including Gupton that was mentioned above). They give incentives/rebates on top of dealer discounts plus tdm coupons and a little more if you join tread lightly for fca discount.