I made a body object, then the feet objects, and using Bool Tool, I joined them together with Union, but I haven't been able to figure out how to make the connections truly connect with correct retopology.
I was somewhat able to make the connections work by using Merge vertices, but it is a pain. As you can see, the normals are all over the place.
Any idea how to make one object with seamless connection?
For a case like this your best bet is probably to make sure the terminal edge loops have the same number of verts, then just join the objects and bridge edge loops.
the above answer is the easiest solution, if that is not possible the next step after the boolean is to remesh (several options on how to...) so that the mesh is returned to quad topology...
hope this helps