if you install the play store and give it perms to install apps Google can see all apps across all profiles anyway. Fact check this but I believe this is the case.
If you install play services it makes sense to benifit from the play store's security with a burner account and if an app is removed or censored use another method to obtain said app.
I can only see the benefit from a main profile and a kids profile. Or just have a main and run FOSS only if that's achieveable for your needs.
#GrapheneOS