It all comes down to battery availability, GM planned a progressive ramp at the Lordstown battery factory and have a lot of demand for the initial batteries in several vehicles. Also they can only set up at Factory Zero so fast for all the different projects going to be built there, and they have the SUT in the market so they want to get other projects launched (Silverado EV, Bright Drop EV-600, Lyriq, and I think we will see more EV launches in the fall this year. I expect GM to show a Chevy EV Crossover, Buick EV Crossover, and an Escalade EV.
Another thing to remember GM is not like Tesla, these are not aspirational dates they give that they might miss by years, GM typically will hit their dates or be early.