Saudi clubs have invited the world's best footballers to introduce themselves to the world. Ronaldo's presence there really brought the league to the top of the discussion. If Al-Hilal club was able to get Messi in their team then maybe the league would have gained better popularity. It was thought Messi would head to Al Hilal after his official departure from PSG, but that didn't happen.
I am not very sure of this because not much he can be done at Inter Miami for his career he can't compete in the Champions League the same thing if he goes to the Saudi League so Messi must have other reasons that we cannot guess. Like what we hear in the media in the end Messi will come to the Saudi League between the next 1-2 years and that's the right time to retire.