rodolphe I don't want to use the Google Play because I don't have a Gmail account. So I want to use Aurora. Is it safe or is it better to use Google Play Sandboxed ?
First of all, what you are referring to as google play is in fact, Sandboxed Google Play Store.
Sandboxed Google Play has a few more dependencies you need to install such as Sandboxed Google Play Services, Sandboxed Google Services Framework.
Aurora store doesn't need these dependencies.
Aurora Store is less secure in many ways but firstly being to trust aurora as well as Google in this terms.
I highly recommend you to use Sandboxed Google Play Store over Aurora Store on your profile where you need Google Play Store apps.
If anonymity is what you are trying to achieve then, I highly recommend you to create a secondary user profile for it.