In the eldritch invocation “One with Shadows”, it is stated that the player is invisible in a dim location until an action or reaction is used. Since movement is not an action, could the player use just movement on a turn or outside of combat and still remain invisible?
Movement breaks the invisibility of "One With Shadows".
The Eldritch Invocation "One With Shadows" states:
When you are in an area of dim light or darkness, you can use your action to become invisible until you move or take an action or a reaction.
If you move, whether on your turn or outside of combat, the invisibility ends.