Looks like a really cool concept, awesome to hear you are already having success.
The wholesale channel is a great way to grow market share, points of distribution & volume for your products. Great that you have identified stores you think are a fit.
As for your question about the approach, I’m not aware of a standard email template for approaching wholesalers. (regardless of the template it can be difficult to get a result from cold email outreach).
The best thing you can do is increase your odds of getting a response by building a relationship and get the information to the right person. Maybe go into the stores you want to carry your product and show the shop staff in person, to get them excited. Then ask them for the name of their manager or accessories buyer. (could also do this over the phone). That way you have staff that like your products, and a name you can follow up with directly.
Once you have the contact, a key piece of information for the buyer will be the wholesale and retail prices. Research the typical margin expectations for similar products. Ensure you have calculated your margins so it is profitable for the retailer & for your business.
I’d be happy to jump on a call if you want to chat.