The hearing aid is only one pice of the equation.
To get a hearing aid to work its best for the wearer, a really good audiologist is needed -sometimes over multiple appointments— to tweak the settings.
If you think a Costco audiologist will give you personalized service, that’s your decision. Personally, I think Costco is great for discount food and maybe travel. But my hearing deserves the VERY best and I get that from my audiologist.