QR code in dev console DNS error

For future reference I found the answer.

Apparently Android phones have an issue with opening deep links, which are links that launch and open apps within Android.

You need to either enable it in your androidManifest.xml like so:

<intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.DEFAULT" />
        <!-- Accepts URIs that begin with "com.shopify.pos://pos-ui-extensions" -->
        <data android:scheme="com.shopify.pos"
            android:host="pos-ui-extensions"
            android:path="?url=">
    </intent-filter>

which I don’t really recommend.

Or download a Deep Link Launcher app from the Play store and paste the link into it.