So it appears that Pippi provides a physical marker that you can place (similar to the Icarus device). But that requires actually physically visiting the location and placing down an object. What I had in mind was really just a simple way of me clicking a spot on my map, and my wife being able to see it on her map, so I can say, for example, “Let’s go to this spot”. Hard to believe there isn’t that functionality available somehow, if only through a mod. But I’ll keep searching, thanks all.