We've built a small utility within our app which would tell you whether your current theme is Online Store 2.0 compatible & supports app blocks. If so, which areas of your theme can have app blocks.
Note that this checks happens on your live theme! So make sure you publish your live theme before running this check.
To do this check, open our app and then on home page you should find banner like following towards bottom of page. Click on "Check theme compatibility" which would tell you which parts of your current store supports app blocks.
Once you run check, you should see something like following depending on your theme:
If you see certain templates being supported, that means you can start using app blocks on those templates and embed validator on those templates. Please follow this tutorial to learn more about it.
Currently we check these templates: 404, article, blog, cart, collection, index, list-collections, page, password, product, search
As Shopify recently announce Online Store 2.0 experience, it would take certain time for theme developers to migrate their existing themes to this new format.