Delta is primarily an Airbus fleet. They do not currently fly any 737 MAX planes, though they have ordered 100 Max 10s for delivery starting in 2025.
I'll assume they're being pressured into it by the significant fuel savings the max offers over their current fleet.
Or, if are willing to fly any of the big 3's regional brands it'll be on a regional jet which Boeing doesn't make. Generally those are made by Bombardier or less commonly Embraer. Though, bigger plane means smoother flight.