Stitch 2 mesh parts like in the UV stiching function I don't know how to 'stitch' these two meshes together. I don't mean a 'bridge', I want the Foot moved correctly into the socket: There is a stitch function for UV maps that does exactly what I want (see the video: https://youtu.be/42XCrtxvhyM?t=519)
As long as the loops match, you can turn on snapping and auto merge in Edit Mode to do this:




Turn on snapping (Shift+Tab)
Set snapping mode to vertex (Shift+Ctrl+Tab)
Turn on auto merge


Then move the part of the mesh: