Phone identity and proxies
Each phone can come from somewhere of its own: every app's traffic through a proxy of yours, and a location, time zone and language that agree with where that proxy exits. It is set by a workflow, with the Phone identity block, and the Devices page shows each phone's proxy in its Proxy column.
The proxy
Add your proxies on the Proxies page — the same list WarpX Browser uses, HTTP or SOCKS5, passwords stored encrypted. The phone's agent carries every app's traffic through the one the identity names, as a VPN on the phone; DNS and IPv6 go through it too, so names are resolved by the proxy.
Location, time zone and language
Each can be set by hand or follow the proxy: the identity looks up where the proxy exits and sets the phone's time zone, language and location to match. Each part is applied on its own and reported on its own, so a failed lookup still leaves the proxy in place. The location is set as Android's test location, which an app that checks for one can tell.
Keeping it on
The watchdog puts a phone whose VPN has dropped back on its identity's proxy, every two minutes at most. Applying the identity again changes nobody's proxy; setting a different proxy, or none, asks before a workflow somebody else made does it.
What the phone says it is
Change device sets a phone's name and screen size and density without root. Its brand and model, as apps read them, need Magisk or KernelSU and last until the phone restarts. Nothing changes what identifies the phone to its mobile network.