I have JavaScript running on my thank you and order status pages via the “Additional Scripts” section in Settings (Settings -> Checkout -> Order status page -> Additional Scripts). On the thank you page, window.Shopify.Checkout has both a cartToken a...

I also could not find a client-side API to get the app's URL within my Checkout UI Extension.You might try using a configuration file / environment file to deploy your extension with your app's URL. Shopify's deploy command has a `--config` flag wher...