Chrome's 3rd party cookie blocking also prevents access to localStorage or sessionStorage. This basically means our app can't function in an embedded iFrame.
Uncaught DOMException: Failed to read the 'sessionStorage' property from 'Window': Access is denied for this document.
Do Shopify have a solution for this?
No, if you're using an embedded app there's no way around it. You'll have to find a workaround. Our app wouldn't get approved unless we removed it.
Apps not embedded don't have this issue.