Native Americans/First Nations people (I don't use "indian" terms because it gets confused with curries) are literally like the smallest general race population in the world. There are so few of them in comparison to the other races, it's quite astounding. Mainly because their societies gor mogged by disease/warfare/loss, etc in the past, so there are not a lot of them left at all, which is probably why there are very few Native American incels.
I mean just to give a personal example I live in the USA. And in a place were like 300 years ago the only people who lived in my area were Native Americans, and out of everyone in my city, I've only met like 1 Native American family (but they were Alaskan natives who had moved here). And I live in a city with >1.5 million people in its metropolitan area so that's not a lot.
Not to mention, most of the non-mixed race Native Americans that are left live on reservations in the USA and Canada, so the have at least some insulation and isolation from the rest of soyciety. Therefore making it less likely that they will be incel and even less likely that they will become blackpilled and post online about it.