After shulker boxes were added any travelling companion carrying items is easily overshadowed by a ender chest full of shulker boxes. So why not embrace your shulker box overlords and add a more modern spin on the old traveling trunk.

The Bouncing Box: an animated shulkerbox reinforced with thaumium or void metal. It would be available after scanning shulkers and shulker boxes. The research would also need an ender chest and maybe chorus fruit, which would explain the teleportation ability of the box. So it would act as an moving shulker box that could be picked up in some way and it would be extra resilient to damage due to the reinforcements and the shulker shells. It would have some upgrades, like attaching an arcane levitator to make it fly or have it act as an moving ender chest. Maybe it could have the other familiar upgrades like picking items up, attacking mobs with melee or shulker bullets.

This would be a cool addition and it would be distinct enough from Thaumic Additions Chester and it would be a cool little homage to the traveling trunk seen in Thaumcraft 1, 2, and 4.