No, this is not a problem.  AMP operates as essentially an independent theme, so if you use a separate theme (for example, the Turbo theme) as your "normal" theme, and you use (for example) the Debut AMP theme as your AMP theme, then there is no inherent problem.  The difference in styling between AMP and non-AMP is a typical experience of any AMP platform, such as AMP on WordPress, or Magento, BigCommerce, etc.  Google doesn't have a problem with the visual variation.  You'll still receive AMP benefits in the form of page speed and SEO.

But why isn't my theme listed on AMP?

There aren't any theme developers who offer AMP versions of their entire theme, so what we're doing is converting popular themes into AMP on our own, and allowing you to choose which AMP theme you'd like to use.  This requires a lot of work on our part, but in doing so, we're able to help thousands of users quickly and effectively.

We're also adding additional enhancements to each AMP theme that we create.  For example, on the Debut AMP theme, you're offered easy integrations with a "sticky" header, announcement animations, quantity plus/minus buttons, and more, all integrated directly into the theme.  These are all enhancements over the original Debut theme provided by Shopify.  We take great care to make sure that our themes score incredibly well on GTMetrix, often scoring between 95-100%.  We're making sure to produce quality before quantity.

Are you going to create an AMP version of my theme?

Over time, we're incorporating more and more themes into our app, each with incredible page-speed and selective enhancements.  We're starting with the most popular themes first, and throughout 2020 you will find many more themes being added to our platform.   If interested, you can also contact your theme developer directly and ask them to collaborate with us, which would certainly speed up the process!

But I want my AMP theme to look exactly like my original Shopify store.

The theme editor that we provide will allow you to easily edit the styling of your shop, such as colors, fonts, announcements, and other styles.  We also have our extremely powerful Custom CSS feature, so you a much more granular ability to fine-tune the look and feel of your AMP pages.  It's unlikely that you'll match your AMP and non-AMP shop up exactly, but our customers often find that the AMP pages, combined with unbeatable speed and SEO, are a fantastic advantage, despite a slight difference in appearance when compared to their normal shop.

What do you recommend?

We recommend starting with the Debut AMP theme, and customizing this theme using our Custom CSS live editor tool.  This tool makes it easy to fine-tune the colors and smaller details of your page.