This year about half of the teams were running engines from Ferrari, Mercedes or Honda. The teams all have to build their own chassis. F1 held off admitting the Cadillac team until the last minute so they are getting a late start, but will join the list of engine suppliers too, in 2029.
The engine development will take place near Hendrick Motorsports’ campus where Cadillac F1 owner TWG’s NASCAR team (Spire Motorsports) is a satellite. The engine folks will come from Cabarrus County, North Carolina (near Charlotte), and numerous staffers (Pageneaud, for example) are based there.
Choosing to launch on NBC is apropos. Comcast owns Sky F1, and the Apple coverage is the Sky broadcast. Also, they could launch it after Super Bowl Halftime because it is Apple sponsored.