I think it's quite difficult for small businesses to do well with nostr at it's present state.
Social media like Instagram, Facebook, etc helps small business grow by reaching intended untapped audiences but without an algorithm to guide new customers into finding them, it is really difficult.
Nostr is good for small businesses to maintain and connect with their existing customer base though. I think the connection on Nostr is much more authentic and intimate. Partially because of its small size and "early internet" feels and partially because of the immediacy and direct nature of zaps.