I’ve met a toddler and a teen named Coven and they wear it really well. I definitely think it’s usable, and the nn [name_m]Cove[/name_m] is cute.
I also think [name_m]Cove[/name_m] could stand on it’s own too.
The only other thing I could think of to get to the nn [name_m]Cove[/name_m] is Coverden
I wouldn’t use Coven for two reasons. 1) Exactly what @bskelton said… a coven is a group of witches. 2) Coven is not pronounced [name_m]COVE[/name_m]-n it’s pronounced CUH-ven so [name_m]Cove[/name_m] as a nickname isn’t really intuitive.
I’ve heard of a baby [name_m]Cove[/name_m], it’s not my style but I don’t see a problem with it either. I think it stands alone just fine!