What the god pickaxe does:
1. You can destroy blocks in adventure mode
2.It is enchanted with the perfect enchantments and levels. For example, you mine fast, but not too fast, where you could accidentally mine a ton of extra blocks
3. It has some attribute modifiers, to enhance the player using the item, leveled up to god level.
4. It is unbreakable, so it will never run out of durability, and it costs almost nothing to repair it in an anvil anyways.
5. It has a custom name and lore, and hides all information about it, like the attribute modifiers and enchantments.