Bigfoots/Bigfeet would have had to have maintained a breeding population over centuries and done so largely in secret. I don’t think they did so. If you see one sasquatch in the woods, you have to wonder how its parents, grandparents, and siblings and the othe sasquatch families escaped detection.
Ishi, the Indian who was the sole survivor of his tribe turned up in the 1900s, but his tribe had been around in the 1850s. I’m skeptical of whether bigfeet could have hidden themselves for over 150 years and yet have been able to breed and raise children.
There’s a huge percentage of this Earth that has never been explored, a lot of it in North America.