Is there uses for which you only want to contain that activity in one profile and only use that profile for it?
How much greater security would this provide for that specific use?

I have a profile for big tech apps, a spare profile for work, a profile for sensitive documents (passport), and banking.

It's just nice to be have separate storage, encryption keys, lockscreens, and VPN connections for these different use cases. There is an added advantage of being able to be certain that all apps in a signed out profile cannot run in the background.

The profile with sensitive documents in it is a little unique. This profile exists so that I can hand my device over to law enforcement, a clerk, or airport staff to inspect a digital document without them being able to go through my whole phone unhindered.

I dont run Google Play services in any of the profiles currently, but may have to in the future for banking apps or similar. But right now everything works fine without Google.

    Can I also use proxy on the Google pixel phone? Or can I set the location to another city?