This setup allows shulker to be inside certain blocks

Zombie attacks baby zombie

Sand going inside shulker/floating above

Gravity affected block on a non integer x or z level

Sand going inside blocks/inside piston head

Piston heads can extend inside of a shulker but the shulker doesn't teleport away with this setup

Not a bug, but a suggestion. You can dye shulker boxes, so why not shulkers?

Can push many gravity-affected-blocks with a piston when stacked together as described.