I want to use something like this, but I don't think I can when also using VPN by Google on an unrooted phone.
Your comment is how I found out about "VPN by Google".
I wonder how old it is and what their motivation is/was. Maybe to offer something comparable to Apple Private Browsing?
It sounds like VPN by Google is an effective strategy for keeping users from using ad and tracking blockers, then; for contrast, iOS routes the connection to the private traffic server over your user VPN connection if one is active.