When I was starting on #nostr there was this small enterpreneur who was trying to advertise their merch to people directly on here 5-6 months ago. They shared their frustration about how to do so effectively, and since it was about expiring food items I suggested back then to them to use nostr.watch and connect to more local to their location relays and there may be a better success with advertising to people who use those and actually purchase (ln bits was still in beta).
#zapvertisement may work to some extent globally, however a future list of relays that support or direct to specific (local or not) communities and marketplaces(nip15) maybe something a lot of people including me may like to see.
A list of relays that support marketplaces would be great both for merchants and customers and would be good to see such a relay-list when gets there, so this project has potential π€