A Grabbable object typically consists of three main components : the 'Grabbable' component, a Rigidbody, and a Collider. Technically only the 'Grabbable' component is required, but you'll need the Rigidbody and collider if you want your object to react to physics.
Here are a few general tips to keep in mind as well :
Try to keep you Object's scale at 1,1,1. Otherwise, Unity physics may behave oddly. At the very least, make sure your scale is uniform.
I recommend sticking to primitive shapes when setting up colliders - Sphere -> Capsule -> Box Collider are generally the fastest. Only use a mesh collider if you have somewhat complex geometry.
Child colliders are not Grabbable by default. This allows you to have more control over which colliders of your objects are considered Grabbable. If you want all of your child colliders to be Grabbable, you can either check the "Make Child Colliders Grabbable" checkbox on the root Grabbable object, or manually add the 'GrabbableChild" component to any child object you wish to associate with the parent.
Unity Rigidbodies have a mass of 1 by default. Colliders typically do not have physics materials attached. You may want to adjust these properties to makes sure your phsyics feels right.
¶ Check out this tutorial by SharkJets on how to make a Grabbable object :