VPN Policy-Based Routing + Web UI -- Discussion

Hi everyone,

I struggled getting a Wireguard server (to communicate with my phone) and a Wireguard client (Mullvad) to run at the same time, but where the traffic from the phone is also routed over the Mullvad interface. In another post of mine (Wireguard setup: Mullvad Client + Server for Android) I was told to ask you here.

I checked the mentioned tutorial (https://github.com/stangri/openwrt_packages/blob/master/vpn-policy-routing/files/README.md#local-openvpn-server-scenario-1), but all I read about seems to lead to a setup, where the client is routed via the WAN interface instead the Mullvad one. Did I get this right? So basically I want to connect my phone to my router via Wireguard and then by checking "am.i.mullvad.net" see, that my traffic is routed also over Mullvad.

So I want: Phone (abroad)-> Router -> Mullvad -> Internet

To answer this question finally: is this possible? If yes, I will try to follow your tutorial (and maby make it run for Wireguard), otherwise it would be great if somebody could explain, why this is not possible and what alternatives I would have.
Thank you all!