A data pack for Minecraft 1.20.5+ which makes empty shulker boxes stack up to 64 per slot.
This pack modifies the recipe and loot tables for shulker boxes to make their max_stack_size component 64 (if it is empty). It also checks your inventory for shulker boxes that are empty but still have a max_stack_size of 1, and modifies them accordingly so if you grab shulker boxes from creative mode or a command, or you enable this in an existing world, the items will be updated once in your inventory.
This pack supports Smithed's Weld feature to merge the pack with others, and uses a modified form of the standard yellow shulker box loot table for use in modifying player inventories.