It turns out some ad/analytics SDKs used by various proprietary Android apps can be disabled/kneecapped by adding meta-data entries to the apps AndroidManifest
In order for an app to read its meta-data entries from its own AndroidManifest it actually has to go through the getPackageManager() call
This means we can change the system package parser and simply add these variables to every app
This would hopefully make usage of proprietary apps more private, granted they are still proprietary and can very well simply ignore these

A simple app was created to verify the expected
05-21 05:24:44.557  4973  4973 D MDT     : firebase_analytics_collection_enabled:false
and it does indeed work!

core/java/android/content/pm/PackageParser.java
	parseMetaData()
		line 5526 if (data == null) {
src/com/android/settings/SecuritySettings.java
res/xml/security_settings_misc.xml
        <SwitchPreference
            android:key="hamper_analytics"
            android:persistent="false"
            android:title="@string/hamper_analytics"
            android:summary="@string/hamper_analytics_summary"/>
res/values/strings.xml
    <string name="hamper_analytics">Hamper analytics SDKs</string>
    <string name="hamper_analytics_summary">Aggressively breaks various proprietary tracking SDKs by unsetting their API keys. May cause low-quality proprietary apps to crash.</string>

Keywords to find keys
	"meta-data android:name" analytics
	"meta-data android:name" app id
	"meta-data android:name" disable
	"meta-data android:name" gdpr
	"meta-data android:name" location
	"meta-data android:name" opt-out
	"meta-data android:name" private key
	"meta-data android:name" secret key

Core - Currently Implemented
            data.putString("android.webkit.WebView.MetricsOptOut", "true");
            data.putString("batch_opted_out_by_default", "true");
            data.putString("com.ad4screen.no_geoloc", "true");
            data.putString("com.facebook.sdk.AutoLogAppEventsEnabled", "false");
            data.putString("com.mixpanel.android.MPConfig.UseIpAddressForGeolocation", "false");
            data.putString("com.webengage.sdk.android.location_tracking", "false");
            data.putString("firebase_analytics_collection_deactivated", "true");
            data.putString("firebase_analytics_collection_enabled", "false");
            data.putString("firebase_crash_collection_enabled", "false");
            data.putString("firebase_performance_collection_deactivated", "true");
            data.putString("google_analytics_adid_collection_enabled", "false");
            data.putString("google_analytics_ssaid_collection_enabled", "false");
            data.putString("google_analytics_default_allow_ad_personalization_signals", "false");
            data.putString("com.ad4screen.tracking_mode", "Restricted");
            data.putString("com.sprooki.LOCATION_SERVICES", "disable");

Settings
            data.putString("com.bugsnag.android.AUTO_CAPTURE_SESSIONS", "false");
            data.putString("com.bugsnag.android.ENABLE_EXCEPTION_HANDLER", "false");
            data.putString("com.bugsnag.android.PERSIST_USER_BETWEEN_SESSIONS", "false");
            data.putString("com.bugsnag.android.SEND_THREADS", "false");
            data.putString("com.followanalytics.message.inapp.enable", "false");
            data.putString("com.followanalytics.message.push.enable", "false");
            data.putString("com.mixpanel.android.MPConfig.AutoShowMixpanelUpdates", "false");
            data.putString("com.mixpanel.android.MPConfig.DisableAppOpenEvent", "true");
            data.putString("com.mixpanel.android.MPConfig.DisableDecideChecker", "true");
            data.putString("com.mixpanel.android.MPConfig.DisableFallback", "true");
            data.putString("com.mixpanel.android.MPConfig.DisableGestureBindingUI", "true");
            data.putString("com.mixpanel.android.MPConfig.DisableViewCrawler", "true");
            data.putString("com.mixpanel.android.MPConfig.TestMode", "true");
            data.putString("engagement:adm:register", "false");
            data.putString("engagement:locationReport:lazyArea", "false");
            data.putString("engagement:locationReport:realTime:background", "false");
            data.putString("engagement:locationReport:realTime", "false");
            data.putString("engagement:locationReport:realTime:fine", "false");
            data.putString("engagement:log:test", "false");
            data.putString("engagement:reportCrash", "false");
            data.putString("FYBEnableSSLRewardedVideo", "true");
            data.putString("mceSessionEnabled", "false");
            data.putString("tapjoy.disable_video_offers", "true");
            data.putString("CLEVERTAP_USE_GOOGLE_AD_ID", "0")
            data.putString("engagement:connection:delay", "2629800");

API Keys
            String apiFillerValue = "";
            //String apiFillerValue = "DO_NOT_TRACK";
            data.putString("apptentive_api_key", apiFillerValue);
            data.putString("apptentive_key", apiFillerValue);
            data.putString("apptentive_signature", apiFillerValue);
            data.putString("__ChartboostAir__AppID", apiFillerValue);
            data.putString("__ChartboostAir__AppSignature", apiFillerValue);
            data.putString("com.a0soft.gphone.aTrackDog.webURL", apiFillerValue);
            data.putString("com.ad4screen.facebook_appid", apiFillerValue);
            data.putString("com.ad4screen.partnerid", apiFillerValue);
            data.putString("com.ad4screen.privatekey", apiFillerValue);
            data.putString("com.ad4screen.senderid", apiFillerValue);
            data.putString("com.appsee.ApiKey", apiFillerValue);
            data.putString("com.blueshift.gcm_sender_id", apiFillerValue);
            data.putString("com.bugsnag.android.API_KEY", apiFillerValue);
            data.putString("com.crashlytics.ApiKey", apiFillerValue);
            data.putString("com.facebook.sdk.ApplicationId", apiFillerValue);
            data.putString("com.geouniq.appkey", apiFillerValue);
            data.putString("com.google.android.awareness.API_KEY", apiFillerValue);
            data.putString("com.indooratlas.android.sdk.API_KEY", apiFillerValue);
            data.putString("com.indooratlas.android.sdk.API_SECRET", apiFillerValue);
            data.putString("com.pushwoosh.appid", apiFillerValue);
            data.putString("com.pushwoosh.senderid", apiFillerValue);
            data.putString("com.upsight.app_token", apiFillerValue);
            data.putString("com.upsight.public_key", apiFillerValue);
            data.putString("co.paystack.android.PublicKey", apiFillerValue);
            data.putString("FAID", apiFillerValue);
            data.putString("io.branch.sdk.BranchKey", apiFillerValue);
            data.putString("io.emma.SESSION_KEY", apiFillerValue);
            data.putString("io.fabric.ApiKey", apiFillerValue);
            data.putString("net.hockeyapp.android.appIdentifier", apiFillerValue);
            data.putString("net.hockeyapp.android.appSecret", apiFillerValue);
            data.putString("pilgrim_sdk_key", apiFillerValue);
            data.putString("pilgrim_sdk_secret", apiFillerValue);
            data.putString("presage_key", apiFillerValue);
            data.putString("tkbl-api-key-0", apiFillerValue);