https://www.discoveryplus.com/video/bigfoot-fear-in-the-woods/bigfoot-fear-in-the-woods
Here are pictures of their work and a footprint found in the area...
Environmental DNA or eDNA is DNA that is collected from a variety of environmental samples such as soil, seawater, snow or even air rather than directly sampled from an individual organism. As various organisms interact with the environment, DNA is expelled and accumulates in their surroundings.