What can't you do on Android WITHOUT a Google Account set up in the OS?

For example, YouTube app functionality can be replaced by the open-source NewPipe app, which does NOT need a Google Account set up on the phone.

Likewise, Google Play Store APK installation from the Google Play repo can
be replaced by the open-source Aurora app, which does NOT need a Google
Account set up on the phone.

Similarly, GMail app functionality can be replaced by the FairEmail app,
which does NOT need a Google Account set up on the phone.

What app functionality from Google can NOT be replaced with an app that
does the same functionality but WITHOUT a Google Account set up in the OS?

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