So, someone else already posted this theory:
https://www.reddit.com/r/OnePieceSpoilers/s/xwfHxBg5Ve
I made this post just to highlight my reply because It’s really simple and I think that’s a really nice touch from Oda.
Chopper is special because he’s pure at heart.
In other words, he’s deeply human.
That’s why he wants to become a doctor able to heal every disease, and that’s why he’s awakening his devil fruit.
He’s the opposite of those scumbags part of WG, the opposite of someone who sold his soul to a devil to achieve power. And now, he’s able to bring that “humanity” back when touching people.
So yeah, Zoro is right, in a certain way. Chopper is really able to do that because he is a great doctor.
Moreover, he is a great doctor because he is a wonderful human being.