lovefromisrael
It is recommended to avoid Aurora Store as it is insecure and dangerous while providing no privacy benefit.
Sideloading (downloading and installing an apk manually) is even worse, especially if you are not doing it directly from the developer but rather from 3rd party websites, as you can't verify the legitimacy of the app.
I recommend installing it and all other Play Store apps from the official Play Store with sandboxed Play Services. This is the most secure method and more private as well. (security is a prerequisite to privacy)
Play Services are completely sandboxed without any special permissions or elevated access on GrapheneOS, just like any other app is.
You can read more here:
https://grapheneos.org/usage#sandboxed-google-play