.com is familiar, .store is specific
.com is still the most familiar extension for many shoppers. If your exact brand name is available as a short .com, it is usually a strong choice.
.store can work well when the business is clearly ecommerce and the .com is unavailable or too expensive. It tells visitors what the site is for before they even click.
Trust comes from consistency
The extension matters less than consistent branding, a secure checkout, clear contact information and a polished website. A strong .store domain can outperform a confusing .com if the experience is better.
Use the same domain across social profiles, email signatures, packaging and ads so customers learn one address.
Start with a subdomain, launch on the keeper
Test your website on a demo subdomain while editing. When you are ready to market the business, connect the custom domain you plan to keep and submit the sitemap from that address.