If I absolutely needed an app that required the Google Play Framework (GPF), I'd install it in the second profile. Many banking apps require GPF, for instance.
Or anti-privacy apps like Facebook, Instagram, Tik-Tok, WhatsApp, etc might go in the second profile.
But honestly I don't plan to and would use a second phone if I absolutely needed to use any of these services. Why expose the phone to unnecessary fingerprinting risk?
If any of these anti-privacy apps share with another, you could segment further by placing them in separate secondary profiles.