First Nations blessing is a bit of a gray area because they are not necessarily performed as a religious practice. Instead of a prayer, it’s interpreted (by those present) more like a First Nations representative formally acknowledging that the decisions about to be made are made with their participation.
It’s a cultural complexity that elders are often also seen as religious leaders and they’ll often speak in religious terms, but their blessing is foremost under the guise of a representative - not a cleric.
As for a regular Christian prayer… its sole purpose is a ritual for those in that religion.