I was thinking about it and what if instead of trying to mimic apricorns/pokeballs, the seeds inside of Hisuian Voltorb is where brown apricorn trees come from?
In Legends Arceus, we never get any comments or observable behavior to suggest that Voltorb receives any benefit from looking like an apricorn and if they do, it makes no sense you can't find it in apricorn trees like you can other pokemon. What I do know though is that modren Sinnoh does not have any apricorn trees and coincidentally does not have any Hisuian Voltorbs. Also, the only apricorn color that exists in Hisui is brown while simultaneously brown apricorns have not been found anywhere but Hisui.
There's not much else I can say as there's not a lot to go off of to begin with with Hisuian Voltorb but I was wondering what you guys think?