I agree with @Dolemite that it’s not about checking a box, but each person owns their ethnicity and should choose to embrace/exhibit it as they see fit.
I’m a tiny fraction Native American and I’m not active in my tribes. I do, however, have my Certificate of Degree of Indian Blood (CDIB) and maintain an interest in Native American history and issues. When asked, I proudly check all the boxes that apply to my ethnic background without hesitation.
It’s yours, you get to choose how and when to use it. Good luck!