I can give you real character developments Luffy has had over this arc alone as a leader. From the Udon prison, and his way of handling things. Yet you zoro fans would just chalk it up to “I’m gonna be pirate King” shit, and be reactionary for the latest chapters alone with him smiling with Kaido.
No you cant, because he didnt went through any. Thats not a bad thing, Luffy was a reckless idiot before Udon and he is still a reckless idiot now, but thats part of the character's charm.
Luffy is definely the character that went through most character development through the series and thats only to be expected as he is by far the character with most pannel time and was a complete idiot at the start of the manga to the point where he almost killed himself, not to mention the ammount of pain he used to put his nakama on before the TS, but that is completely irrelevant to the argument, as the innitial discussion was about how you vomited on your keyboard and said Zoro didnt had any character development.
Zoro saying Luffy would be PK is not a character development either, its a well known fact he has faith in Luffy for a long time now, if anything it only reinforces how and why he is Luffy's most dependeable nakama. There has been over 1000 chapters o this manga, theres a limit on how much characters even can deveop.