Common ecommerce solutions such as WooCommerce are not supported, however, there are other options available.
The reason that plugins including WooCommerce and are not compatible is that they require PHP for a few necessary functions including cart features and payment processing.
To bring fully-functional ecommerce back to Shifter opt for solutions that offer ecommerce as a service and include embeddable shop scripts.
For example, PayPal, Stripe, and Square to name a few all offer copy and paste embed codes that allow you to sell products on your WordPress site. The benefit of this is that when Shifter creates a static version that functionality remains the same.
In addition, this method offers faster a checkout process, improved page speed during peak traffic, and it'll always be secure with HTTPS.
With a few short embed codes copy and pasted, users can combine their custom WordPress themes with existing Square accounts.