There are 3 types of Movement with an XR Grab Interactable :
Moving while holding an object:
Kinematic
- Has a short lag to the movement.
Instantaneous
- Solidly follows along with movement
Velocity Tracking
- Has a short lag to the movement
Physics
Kinematic
- Objects go through other objects
Instantaneous
- Objects go through other objects.
Velocity Tracking
- Objects do not go through other objects
Interacting with other Rigidbody
Kinematic
- Moves other objects with ease.
Instantaneous
- Difficult to move other objects and collides very solidly
Velocity Tracking
- Moves other objects with ease.
To summarize, I've color coated the differences and similarities between the movement type for an object. For an object like a flash light, and depending on the game, a Velocity Tracking movement type flashlight be best due to not being able to clip through other objects.