That is what I mean. Starting at the Webflow personal plan you can export your project. This will give you a zip file with all of the HTML, CSS and JS files that make up the project. From there you can integrate your project with any system that allows you to modify HTML, CSS and JS.
Both Shopify and BigCommerce are hosted e-commerce / CMS systems. You can create blogs and allow clients to change content on their pages from the site dashboard. The hosting and security is handled by them.
You can also use self hosted solutions. Like you mentioned, Wordpress and WooCommerce, Magento
For some clients I have used Modx and miniShop2 extra.
As you can see there are many options out there