Thanks for reaching out, glad to help answer your question.
Firstly, it’s important to realize that your preference of attraction is totally up to you, and it’s something that’s personal to each individual. There’s no problem in wanting to learn more about Native Culture as well if you are coming from a place of genuine curiosity and interest. Although I’m not too familiar with many Native dating sites, if they require you to be Native it’s never okay to pose or pretend to be another race/ethnicity. If Non-Natives are allowed, then you’re good to go as your preference of attraction is your business only. Maybe a Native would be interested in learning something about your heritage, who knows? More importantly, just be yourself!
You might find the link below helpful for ways to be an ally if you’re interested in learning more about Native Culture: https://www.wernative.org/ask-auntie-questions/how-should-i-as-a-white-person-respectfully-talk-about-native-ancestry