GrapheneOS is the most private & secure degoogled operating system. This operating system does not communicate with Google’s Services at all by default. GrapheneOS is for people who want to reduce their exposure to data collection completely and are willing to put in additional work when migrating to your new phone.
CalyxOS focuses on providing privacy to the average person, without compromising usability. This operating system is for people who want to improve their privacy and protect their personal data with the least amount of stress. CalyxOS runs 99% of apps that are available on iOS or Android by default.
Additionally, CalyxOS runs smoother on older devices & provides software updates for a much longer peroid of time vs GrapheneOS. CalyxOS is recommended for Pixel 3a & Pixel 4 devices.
Google Play Services
GrapheneOS & CalyxOS are privacy focused versions of Android developed from Google’s open-source version of Android called AOSP (Android Open Source Project). Many Android apps require various “Services” that Google offers to operate properly. This could be for timely notifications, figuring out your location, verifying your devices operating system, and more. Google Play Services are NOT required to run most open-source applications.
Many standard applications like Youtube, Banking Apps, Uber/Lyft, Cash App, etc, may not work properly or may not work at all without using some version of Google Play Services. That said, most applications and services (Lyft/Uber/Banking Apps) can be accessed via the browser and do not require installing an app on your phone. Furthermore, many apps have open-source alternatives that are as good or better (Youtube > New-Pipe). If you need access to certain mainstream apps on your phone, you will need some version of Google Play Services.
CalyxOS has integrated MicroG, an open source replacement for Google Play Services, into its operating system. MicroG has created their own version of a limited number of Google Play Services so that most apps will function properly. (You can also install MicroG on GrapheneOS, but it is not built into the OS)
With GrapheneOS, you have the option to install “Sandboxed Google Play Services”. This version uses official releases of Google Play Services, but restricts their capabilities & access to data on your phone based on what permissions are set. Additionally, some services such as geolocation are re-rerouted to Graphene’s own service. The best setup is to install Google Play Services on a seperate user/profile on your phone which essentially gives you two phones in one. Your main user can be fully degoogled, while your secondary profile is fully compatible with whatever applications you need. This way, your phone will not be communicating with Google by default and you can selectively choose which apps have access to Google Services.