PK needs to be minimum Yonko level, otherwise Yonko captures you (as they captured Luffy, Kid, Hawkins, Apoo, Bonney, Pedro, Bege etc.) and it's over. There is no logical way to be PK even if you steal the road poneglyph only, you still need to fight and not lose against the Yonko, there is no escape they will keep coming, even if you miraculously reach the final island without fighting or defeating a single Yonko when you returned to the new world, every other pirate would come for your ass because they know they can beat you easily, especially the Yonko. That's why Rayleigh trained Luffy in combat skills for 2 years and not for anything else, and that's why experienced people like Chinjao and Yonko Big mom herself said being PK is about power.
But Zoro fans will deny this since they don't want to accept the hard fact that PK / Yonko > their favorite WSS mihawk and zoro in terms of power, because mihawk already said being PK is even harder than surpassing himself, they can keep believing a nonsense like it's about the crew and finding the last island only, not about power.
And the newspapers are giving the information to everyone, if everyone knows that a pirate who is weaker than Yonko reaches the last island, then everyone would also know that it was luck or something else, they wouldn't accept that pirate as ''king''. For example, most people don't even accept Luffy as fifth Yonko even when the newspaper said so, it would be the same if someone weaker than Yonko finds the last island, no one would give a fuck, it would be a joke and dubious title.