Enchanted Pick won't give xp

Obviously, with a mending pickaxe, your XP will be consumed to repair the pickaxe, so you don't gain 100% xp you get unless your pickaxe is at full durability; I think if the pickaxe isn't at a bad durability, like 90%, you'll even get some xp.

That's what Mending does.

https://minecraft.gamepedia.com/Mending