It's a command line thing, and I have no idea what that command is. I'll be on in a bit to dig around for whatever 709 left me. But, I could use a spare.
FWIW, I made a repair oops on the anvil which is how I lost the pick in the first place. I get ain't-played-enough-the-past-two-years doof points for that mistake.
Here's a thing I found which might be it:
/give @p minecraft:diamond_pickaxe{Unbreakable:1,Enchantmen ts:[{id:efficiency,lvl:1000},{id:fortune,lvl:1000}]}
If that works, you can just drop them* in a chest on my island.
* "Them" is up to you. I won't cry if the chest is full!