Unfortunately Al is not going to give us any non public information. As for people thinking the Hummer EV reveal was a scam, there is one group of people who thought that, and they are Tech people, who follow Tesla for the most part. They think because Cybertruck ran and drove it was more production ready than the Hummer EV. These people however do not realize how the real car industry outside of silicon valley works, Show Cars at their time of reveal often do not have full capabilities, and the Hummer EV show car was intended to drive out on a stage in a May 2020 reveal and go on a turntable and let media get its first look at it. Thats it.. GM also built a show cutaway so people could see the chassis, structure, and Ultium system. This is standard Detroit rollout fare. Then COVID happened which changed all the plans to the online reveal which actually sucked. As much as the online reveal sucked it did drive tremendous traffic to GMC's website and did bring a massive amount of press coverage, so I guess the product is what mattered, and the word got out that there is a new sheriff in town. haha!
I do not think you will see first Hummer EV sales moved up from fall 2021, GM will not release the Hummer EV for series production until it goes thorough the full development testing phase, this requires Winter and Summer certifications. If I was a betting man, I do not think you will see production of salable models until November 2021, even though production for GM's captured long term test fleet may start earlier than that (summer). The part of the Hummer EV schedule that may be moved up is the lower equipped models as they ramp production. All of this hinges on battery supply from Lordstown OH, and demand from customers.