I have seen this gadget on IG and got immediatley attrected by the idea to use a 2nd monitor for checking perspective(s) to shoot.
E.g. a) using mounted Smartphone to shoot a certain setting/perspective b) start shooting with remote, c) walk across the scenery, creating some movement or some kind of story, d) stop shooting with remote, e) relocate camera position to shoot a different angle/scenery, Repeat a) to e).
You can create a few clips shooting your activities, combined together later on. And every view is in your control. Very useful tool.