Priscilla Ashvane has one, so its very likely there are others with Heart of Azeroth…
Plus, we have like multiple uses of Azerite already like machines, cannons, bombs etc so its rather stupid for people not to be using variations of Azerite in spells attacks and weapons (Ashvane made azerite weapons) so its not like there’s one guy with the heart…
Same as with Legion and Class Halls, there’s no way a single guy/girl had all spec weapons…considering how lore-wise some of the, are very delicate and restrictive to use example: the Affliction scythe who lorewise absorbs souls until it absorbs the users soul and find another user, its kind of impossible to think a single Warlock could wield that, along with the freaking scepter of Sargeras and Thalkiel. There were likely three powerful people in this case.
I think its similar with HOA, but we have to confirm with Chronicles 4. Everything is speculation up to then