Ronaldo is just doing public relations for the Saudi Professional League. There is no way you can compare the French League and the Saudi league in terms of quality and every other aspect. A league that is spoon-fed by the Saudi government. The French League generates funds to run the league while the SPL depends solely on the government to survive. How many players have the Saudi league groomed and had moved to top clubs in Europe. The Gulf League is in its infant stage and needs time to grow to compete with League One. The SPL is not in the same standard even with the Swedish League.
It's part of his deal with Al Nassr but even at bigger scale, with PIF, and Saudi Arabian government as part of their national plan for hosting World Cup 2034. Al Nassr is one of four clubs from Saudi Arabia got investment from PIF, and they use their abundant budget to build up their club squad and the Saudi Professional League.
Without strategic investment from Saudi Arabian government through PIF, Al Nassr would have not signed a contract with Cristiano Ronaldo and many star players from Europe. I believe that PIF will try to keep Cristiano Ronaldo in the league, but he can change his club from Al Nassr to Al Ittihad or Al Hilal, the bigger purpose is growing up the league, not only a single club.