@tiggers Interesting additional information, thanks for summarising.
I have some inside information, so will not comment directly on Andretti F1, but will talk a bit about Haas and their entry into F1 to illustrate what has changed.
When Haas joined F1 they linked up with Ferrari in as close a deal as was possible. In fact their business model was to do as little as possible and pay Ferrari to do as much as possible for them. The key area was the use of the Ferrari wind tunnel in Italy, which they could use as often as Ferrari would allow them. Which then enabled them to swap Ferrari and Haas aero staff at regular intervals. This meant that their first few cars were good cars, whilst helping Ferrari be more competitive as effectively they had more time in the wind tunnel. Paddy Lowe at Merc F1 went to the FIA and got the rules changed to reduce collaboration possibilities, once it was clear that this had happened, so this is not possible anymore. Then McLaren and Renault went to the FIA after the Racing Point copying approach gave them a fast car for one season until the car aero rules changed, and got this approach banned.
The Haas approach had big advantages in enabling the team to achieve very good results for a new team, even finishing 5th in the constructors in 2018, but then they went backwards and look like the team who will struggle to not be last in 2024.
In summary, if you are a new team coming in, you need to be doing something clever and different to have a chance against the other teams in your early seasons, as there are no really weak teams now (compared to when Manor and co joined F1) as they all have a stabilised and consistent development process, based on lots of joint experience, which a new team cannot have.