The manufacturer teams can be ruled out for the same reason. We can’t see Porsche teaming up with Ferrari, Mercedes-AMG, Aston Martin, or Alpine. That leaves Haas and Williams, who already have power unit suppliers they’re happy with. Well, at least Williams is satisfied with its Mercedes engine. The jury is still out on whether Haas will stick with Ferrari, given its widely publicized reliability problems. Andretti Autosport is partnered with Cadillac, though its entry into F1 is still up for approval.
As late as December 2022, Porsche still said that F1 is an area of interest, but now it’s too late. While the new regulations are three seasons away, work on the new power units is underway. That’s why all the teams made their announcements so far ahead of the actual regulation change.
It’s a pity Porsche couldn’t find a partner, and entering by itself would be too expensive and nearly impossible, given the general attitude towards new teams.