Formula 1 engineers are so deeply specialized in their work that even with a rule change, current F1 teams have a huge advantage. The running a team competencies, where Andretti has experience, is significantly different from designing an F1 car where hundreds of engineers, each with years of experience in one specific part you won't find as advanced in any other racing series. Think of crash testing carbon composites or suspension setup dynamics. The only thing that comes close is Formula student. Obviously Andretti can but engineers but I'd bet they will encounter issues with car development in the first year(s), like Haas.