Thanks for the input everyone.
Why go to such lengths as using another app to password protect apps separately? There is already one that you have, called lockscreen. With the time delay for entering password, even 4 digit PIN is sufficient to protect you from brute forcing your phone and it takes couple of seconds longer than fingerprint unlock.
Yeah maybe your right, I already use a 8 digit PIN in stead of fingerprint and 1 min auto-lock so maybe I'm just paranoid. I only lent my phone to people I trust so the separate app PINs is only meant as extra protection in case of theft.
But now with GrapheneOS I have a separate user profile for some apps.
I use separate user profiles for apps that require GSF and GSF+Play but I have a few app that I rather wouldn't have to move to a separate profile. But thanks for the input,