Accessing Metafields in post-purchase extension

Hello, I have to make an API calls in my post-purchase UI extensions, so I am forced to hardcode my backend URL in the code. I am passing the metafield with the URL on the app side, but can’t access it on the extension side.

useAppMetafield hook doesn’t work either. I am getting an error that it can be used only in a checkout UI extension.

Is there any way to pass some data string dynamically to a post-purchase extension?