Hi,
for this you should use a virtual plane in front of the camera and use the action "ScreenTo3dPlanePoint" on the ecosystem,
get your screen point, and define the plane in the 3d space ( along the z axis of the camera at x distance) where you want the corresponding 3d position.
use that to control a dummy object, and have your coin moving towards that dummy, and once locked, make it a child of it. you will have a problem of scaling, so I would suggest that your dummy is visible at least during editing and scale it up so that it fits your UI, then adjust the scale of the coin as you move towards to end up fitting in that dummy object ( use a sphere collider to witness the size of it without showing it in the game view)
Bye,
Jean