"Andretti had signed an engine supply contract with Renault but that expired in March 2023"
"Andretti had signed an engine supply contract with Renault but that expired in March 2023"

Viele Hürden für Andretti: Mit Motorenpartner, aber ohne Motor

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.
I thought the regulations required any additional teams to use Renault engines since they have no customers?
Or does Renault just get the first option to be the supplier?
If a team doesn't have any contract with a PU supplier, they are assigned Pu with the least customers.
If Andretti enters in 2025 and don't have a PU deal, Renault will be forced to supply them. If they enter in 2026 or later, there are three PUs with only one team: Renault (Alpine), Honda (Aston martin) and Audi (Sauber), so any of them could be forced to supply them.
Making a contract ahead of time was important to show Andretti has no yolo attitude about entering the competition.
Fair point. I suppose the lack of interest from Renault to renew the contract indicates they wouldn't be required to supply Andretti.
I wonder who they would end up going with if they do enter as a constructor.
Something like that, I think the way it's worded is actually the engine manufacturer with the least teams they supplied.