Stop 'in app' ads from loading? I noticed that ads inside apps are not loaded when Google Play Services' data connection is disabled and kind of formed the idea that it is responsible for loading these ads within the apps.
Is there any particular package (com.google.*) that I can disable to prevent ads from loading, that is, is any particular package solely responsible for this task (loading ads)?
Is there a way to stop these ads by disabling some such package or system app that would still let me use gmail, play store and other such services?
I am not looking for external ad blocking apps.
App are self-contained. Even for ads delivered by Google AdMob there is no ad-system component involved at all. Apps are loading ads and other data directly from the Internet.
Therefore what you want is not possible. You can disable every app package by Google on your phone, as long as Internet still works the apps will show you ads.
The only system package that might be used is the WebView - a component that allows apps to display web pages - and ads are typically web content.
The problem is that many apps also use WebViews for displaying non-ad content, some apps even mainly consist of an WebView and the whole app consists of web pages.
The used WebView can be configured in Android developer options. On some devices there is a separate WebView component installed, on other the default Webbrowser or an installed Chrome app is used as WebView provider.
It is possible to develop an app that provides an WebView with integrated ad-filter but I have not heard of such an app.
Ad-blocking webview
It seems like there are already such apps available. Base don the information I found Adblock Browser should provide a WebView implementation with integrated ad blocking (not yet tested).
You have to install this app and make it the default WebView provider as shown in this answer.
However using that app has one major disadvantage: It bases on Chromium the open source part of Google Chrome. Therefore all vulnerabilities found in Chrome also applies to this web browser. So if you want to stay secure every time an security update for Chrome is published (which happens some times multiple times a week) the developers of Adblock Browser need to update their project, incorporate all necessary changes and also publish an update. Otherwise app that use WebView for regular (non-ad related) purposes may otherwise vulnerable to an attack.
In the end this is an advantage of ad-filtering external apps like Blockada or on network level in your Wifi network you can install a gateway like Pi-hole. Both filter apps and Pi-Hole work very similar. You don't need to update them so often as security vulnerabilities are not so often found in such apps/systems.