I would guess it's "possible" but also there is probably a lot of logistics involved in "take my poop and put it into your guts".
Back fifteen or so years ago I saw a video somewhere talking about some people doing this to help with an immune condition. What I remember was basically, "We put my poop in a blender with some water to thin it out, and then they stick a tube up their butt and pour that in"
Sounded like it wasn't just a one time deal, more something that needed to happen on a regular basis.