I mean yeah it’s completely different when the plot is literally about finding the planet.
I don’t know if I’d describe “The Rise of Skywalker” as being “about finding a planet” anymore than I’d describe Return of the Jedi as being “about finding the Death Star II.”
You’ve gotten to the point where your argument doesn’t make any sense.
The plot is about THE HEROES finding the planet. Whether the bad guy finds it in the beginning or not doesn’t functionally affect their journey at all, really, which is partially why the Mustafar Minute feels as useless as it does. It’s prolonging the beginning of the movie for the sake of making the Emperor’s appearance feel like a payoff when it’s function in the story is THE SETUP.
Exegol is supposed to be a new, unknown factor for both parties. If Kylo just waltzes up at the start of the movie it raises all sorts of new confusions.