Little as in what? You're being very vague. Do you want to use official Google Apps without the Google APIs? At least the OS is open source, but I can have a very functional device without needing gapps. Same with COS on their cloud platform. Apple is actively preventing users from even installing apps outside their app store.
I think by now it is common knowledge in anyone interested in this subject. A good place to start is this ArsTechnica post from 2013 (updated in 2018) [1].
One nice user on Reddit made a list [2] of AOSP apps replaced by Google:
Google Services Framework removed in 1.1, replaced by Google Play Services
Search removed in 1.5, replaced by Google
Music removed in 2.3, replaced by Play Music
Browser removed in 4.2, replaced by Chrome.
Calendar removed in 4.4, replaced by Calendar (G)
PinyinIME removed in 4.4, replaced by Google Pinyin IME
Gallery removed in 5.0, replaced by Photos (G)
Messaging removed in 6.0, replaced by Messages (G)
Camera removed in 6.0, replaced by Camera (G)
LatinIME removed in 6.0, replaced by GBoard.
Contacts removed in 7.0, replaced by Contacts (G)
Phone removed in 7.1, replaced by Dialer (G)
Clock removed in 8.1, replaced by Clock (G)
Calculator removed in 9.0, replaced by Calculator (G).
This extends to APIs too. For example, Android Location API [3] has a very nice warning on the documentation page:
> This API is not the recommended method for accessing Android location.
The Google Location Services API, part of Google Play services, is the preferred way to add location-awareness to your app. It offers a simpler API, higher accuracy, low-power geofencing, and more. If you are currently using the android.location API, you are strongly encouraged to switch to the Google Location Services API as soon as possible.
To learn more about the Google Location Services API, see the Location API overview.
Hope I removed some vagueness left by my previous comment.
Android Location API uses Google services to provide better location data using Wifi hotpsots and other devices. I wouldn't expect to be able to use Google services without Google. You don't have to use it and get accurate results without it as well.
As you can see they also provide examples of alternative apps that can be used that do not rely on Google, or you can install F-Droid and use apps from the open source marketplace that are open source as well.
This is much more than Apple, who won't even let you install apps outside their app store. While it would be nice for Google to open source their apps as well, they aren't necessary and there are plenty of alternatives and phone manufacturers who have built their entire reputation on providing an alternative to the Google experience while using Android.
> You don't have to use it and get accurate results without it as well.
And this can be applied to nearly every 'improvement' in all Android releases. Can you name any improvements to AOSP in the past five years? All I see on every their presentation is more and more Google Services, FCM, Assistant, etc.
Because that is all the Google apps are really, are one iteration of a group of apps for functionality. You can always use F-Droid and install great open source alternatives.
The fact that you can install a different operating system on some android phones doesn’t mean that the Android that phone manufacturers actually use is open source.
Indeed the fact that you have to install a different operating system that isn’t even called “Android” proves that Android as people know it is not open source.
If you remove everything Google from Android 19, you'll be surprised how little it can do.