You used to be able to set up different user profiles on Android - I set one up just for WhatsApp, and only WhatsApp contacts went in it.

I am dismayed to find that my new Android phone no longer has this feature, except as part of some bullshit "work profile" nonsense that apparently isn't possible for me to set up by myself, on my own phone. "You'll need a code from your IT admin", I'm told, and "a management tool will be downloaded and used by your IT admin to manage your work profile". Great.