I want to make the player’s Marker 2D (and ONLY the Marker 2D, not the player) follow the mouse in a circle around the player, and also visually represent this with a sprite that will alway follow the Marker 2D, how can I do this?
Forget the marker, use a sprite. The sprite will be “top level” meaning it will not listen to parent transformations.
Add a script to the sprite that uses the _unhanded_input function. Check the incoming events are mouse motions and use the relative motion to move the sprites position.