I suspect it's a belief that's been coopted to form into the LGBT ideology. Technically as far back as recorded history in Mesopotamia we've had femboys as a loose concept, but we don't really know what their views on "gender" were, beyond fertility. If anything it may even have been rigid gender roles that portrayed men who broke said roles as feminine (artwork depicts males dressed as females if they were priests of specific goddesses for example / men who were bottoms for other men were seen as feminine).
I would bet money the two spirit shit is kind of in that line of thinking. The male berry pickers would be seen as feminine, and some may have embraced that role, but does that mean that all trans ideology is correct?
This is coming from someone with 0 knowledge of indigenous Canadians, or much about"two spirit" itself, so idfk how close or far off I am.