I was able to special order my Bison for under invoice. That was pre-pandemic, so your mileage may vary. I shopped dealers all over the country based on recommendations from people who had done fly-n-buys trying to find the best deal. I called my local dealers as well, because why not, and was very surprised to find the best deal locally. A lot of that likely had to do with the salesperson, but the owner of the dealership was involved to some degree, and it still obviously went through. I'm sure if you aren't picky, and you find a stale truck on a lot somewhere, you can get a better deal than I got. I'm also sure special ordering a limited allocation vehicle for less than MSRP is not common. Especially on a high demand vehicle that doesn't seem to enjoy the benefits any of the sales or incentives ever, even in a common trim. I'm further sure that if you're an adherent to the church of the proper break-in (meaning you want as close to 0 miles on the odometer as possible when you take possession), you're going to be hard pressed to do better as well.
At the Jeep dealership, and granted this was right as the Gladiators hit the dealership lots, it was "full MSRP or pound sand" (the salesperson didn't care for that phrasing, but didn't dispute it), and surprisingly [/sarcasm] they only seemed to have fully decked out trucks, and one non-Rubicon they would actually let you drive and/or unlock so you could see the interior... I've read or been told that they started to sell a bit less quickly than expected once the novelty wore off, and there were deals to be found on occasion. I've not personally verified this though. I can say that even in this very truck, very off road, very Jeep market, Gladiators are few and far between.
One thing I really like about the Gladiators, so that I don't come off as some sort of Colorado shill, is they're ugly in a good way. One of my favorite, if not my absolute favorite cars I've ever owned was my VW bus. 62, panel, rattle can paint job. Ugly as sin. I once picked the owner of the company I worked at up at the airport in it (instead of his Range Rover which, like Range Rovers do, wouldn't start), and he was PISSED to be seen being picked up in such an ugly car (it was a bit insulting at the time). I like ugly cars when the ugly is due to engineering/practical/etc. reasons. Pontiac Aztek? Get that out of here. That's committee ugly. Fiat 600 Multipla? That's the good kind of ugly. The Gladiator has some marketing stink in the design (not all of it bad), but there's a lot of the good kind of ugly to it. I really like that they took the proven parts of the JLU, and smashed them together with the proven parts of the Ram 1500. You have a whole new platform with none of the growing pains. Yeah, there are some really "whuh?" elements to it, but they tend to be for good reasons. I'm thinking specifically of the kink in the rear doors that makes no sense at all and looks out of place, but that cuts cost (for production AND future used parts procurement) by being shared with the JLU. There are a few little details like that that I find endearing in a "good ugly" way.
Which reminds me. One more point for the ZR2 camp: parts availability down the road. The Gladiator will OWN the aftermarket, no doubt. That will make it easy to do some wild things for sure. But the Colorado will OWN the yards and second hand markets. They're much more popular in the consumer market, but it's the fleets that make it. If you get a white truck especially, you will have a ready supply of inexpensive, OEM quality, ready to bolt on parts forever. Certain mechanical parts will be a little less easy, since those are specific to the much lower volume ZR2, but I doubt they'll dry up prematurely and those are the ones the aftermarket will gravitate to. Those less available mechanical parts though... Military surplus! GM won the ISV contract, and that's a diesel Bison with a tune and different body work. That means in a few years they'll start hitting auctions, and you'll have a complete rolling chassis of all the best bits for pennies on the dollar!