According to this article (20 August, 2018) from Android Blog we can publish instant apps without associated URL:
Today, we've made it easier to build instant games and apps by removing the URL requirement. Previously, in order to publish an instant game you had to create a web destination for it. The website also had to be connected to the instant game through intent filters and digital asset links verification.
Now, it is no longer required to add URL-based intent filters to your instant game. People will be able to access the instant experience through a 'Try Now' button in the Play Store or Play Games apps, via deep link API, and in the future through the app ads.
I've followed the latest Android guide to enable instant experience in my game. The guide doesn't mention anything about required URL verification. The app works on local device, but when I try to publish it to internal test track, I see the following error:
Your Instant App APKs do not declare at least one web 'intent-filter' element with the attribute 'android:autoVerify' set to true in the Android Manifest.
Is it possible to publish instant app without associated URL? Like it's explained in the Android blog post with standard intent filter below:
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
Probably Google has updated all guides but has forgotten to remove this check during instant app publishing? I hope so, because I don't want to create a web-site to be able to publish instant version of my game.