Check out Google’s full guidelines for listing your business in Google.  It should be fairly obvious that local SEO is not appropriate for 100% e-commerce businesses.  That’s because there is no physical location for customers to visit the store.
Think about how annoying it would be to see e-commerce businesses listed when you’re searching for a nearby coffee shop.  You want a place to grab a cup of coffee, not an online store to get coffee beans delivered.
The basic rule of thumb is that local SEO is a good opportunity for any business that interacts in-person with customers, clients, or patients.  If you never meet in-person, then it’s not a good fit.