Container in multi-wan

Hello everybody,
I have some apps running into different containers on a host.
Host is a pc running Ubuntu 20.04 and is connected to a RPI4 running Openwrt.
The RPI acts as a router and is connected to multiple modems (few smartphone in usb thetering).
What I want to do is to forward traffic to internet from container A through smartphone A, container B - smartphone B…
I think I can use macvlan networks for containers and mwan3 on the router, but I can’t find proper information on how to set up all together.
Can anybody please help me?