You're fighting a losing battle
Boa already has coc. And her island is literally full of haki users. Her predecessors are important people like Shakky and Gloriosa who were in Rocks pirates and shit. Boa's sisters have advanced coa already.
Given all that, it's pretty easy for Boa to get acoc.
Where as, Nami only has a single gag scene to her benifit. And that's all it is. A gag scene.
I'm afraid you'll lose this bet
Nami isn't a fighter like Boa or the rest of the coc users. And she doesn't have to be. She's great just the way she is. She doesn't need coc or acoc to shine. She is the heroin of this story. So take solace in that