As I've said elsewhere, there can be assumed to be only two kinds of Android apps on the Google Play Store.

One, those that are also on F-Droid. F-Droid requires everything to be #OpenSource, for F-Droid compiles all apps itself. You can't submit binary blobs to F-Droid, even if they're licensed under the GPL.

Two, everything else. Unless it explicitly says otherwise, everything else has to be taken as #ClosedSource. And non-free, closed-source apps are way more often than not ripe with libraries that "phone home" to Google and Facebook. With no user consent. With no chance to opt out other than by third-party means. Without even telling the user. In fact, even if an app is said to be open-source, that doesn't mean that the binary blob submitted to Google was built from the publicly-available sources.

iOS doesn't even have anything like F-Droid. And iOS puts obstacles in the way of providing open-source apps.