Is using Polaris possible in a post-purchase app extension?

[crossify]

I am building a Shopify post-purchase extension. I would like to use Polaris but it does not seem supported.

For example the following code yeilds this error:

return (
    <AppProvider>
        <Page title='test'></Page>
    </AppProvider>
  );

ExtensionSandboxPostPurchase.latest.en.60c73383f0f7ed657108.worker.js:1 Uncaught (in promise) Error: Unsupported component: h1

Is it possible to use Polaris in an app extension?

[Strydar]

Facing the same problem, Is there any way to use Polaris for extensions? 
If not, how else can we build a good UI for post-checkout applications