I'm a Fella of Fate
I mean... we are practically post wano now. How to you expect Carrot to invited to the crew?
2. Things go wild style on Wano with Carrot taking a big part in saving the day, Luffy asks her based on that
3. Oda pulls a gag where he just has Carrot go with the Straw Hats with 0 acknowledgement until it's addressed after they leave Wano
4. Oda pulls a stowaway gag again and has Carrot (and Caribou potentially) show up on the ship out of nowhere
5. Carrot and Yamato start tusslin over who gets to join and Luffy says they both can