To get the ball rolling, Andretti had already signed a preliminary contract with Renault years ago. But that expired in March 2023. And at the moment, the French are showing no great desire to resume negotiations on a continuation. Renault, alias Alpine, does not want to get caught in the crossfire of a power struggle between the FIA and FOM.
That’s not true. They stated towards the press that GM will be involved in technical aspects without going into details but it’s not really that hard to guess with parts those are:
GM has the facilities such as including several wind tunnels, aerodynamicists, engineers, and so on. At the very least the GM facilities will be used, potentially some personell as well.
Alfa Romeo is not involved in Sauber’s technical aspects at all. GM’s involvement will definitively be more than that.