To be honest I would feel bad adding this hashtag to a marketing post. Doesn't look appropriate for me.
Discussion
Visibility, not marketing. Trying to sell something? Use hashtags related to what you are selling.
Grownostr is for posts that aren't about Bitcoin, like gardening, hiking, or literally any other topic folks might be interested in.
The idea is to go to the grownostr hashtag if you want to find new people to follow, not stuff to buy.