GOS's intended audience are those who are in danger of being hacked or persecuted, not privacy conscious users trying to escape surveillance. Google, for all their faults, is pretty unlikely to hack your phone and reveal your secrets.
See the "degoogling" section.
There's many privacy features that work to allow users to use anti-privacy apps like WhatsApp with more privacy. Contact scopes, storage scopes, sensors permission, network permission, VPN leaks fixed and enhanced secondary profiles.
Plenty of less scrupulous surveillance companies like Facebook take advantage of security flaws for their surveillance so it's important to start from a secure baseline to guard against this threat.