If you want ignore the Closeby launcher completely and embed the Closeby locator directly onto a specific page, you can do that with an <iframe> element. Find you map key by visiting your maps page and clicking "Install Map" in the top right.
Because of Shopify's theming, you will need to edit the theme's code itself in order to install the map within the page.
Once editing your Shopify theme, add the following HTML code to your pages copied from your maps page. Change the "width" and "height" attributes to values that work well on your webpage.
<iframe src="https://www.closeby.co/embed/<:yourmapkey>" width="100%" height="600" style="border:none" />
To restrict your map to a specific category, you can do so by following these instructions.