Automatically sync the Shopify products with Google Shopping and advertise them across Google's Network
Google is continuously optimizing its algorithms to detect when someone intends to buy a given product. Thus, if you want to tap into another profitable marketing channel, you should try Google Shopping ads.
Target or retarget potential customers on Gmail ads. Analyse the cost per conversion and retarget on desktop for more sales.
More than a billion people use Gmail every month. If you can build a profitable campaign, you will be able to tap into a really wide audience.