I've been using Sidebery and this for container specific proxy configuration and it works fine https://addons.mozilla.org/it/firefox/addon/container-proxy/

I had a socks server running in docker that turned Forticlient, the worst corporate vpn solution ever, into socks so then I could use access the internal urls in one container, still have fast internet elsewhere, and not expose my computer's entire network traffic to Forticrap.

I've done this in the past to assign a different exit node in Mullvad to a given Firefox container.

1. You click the Multi-Account Containers extension icon

2. Select "Manage Containers"

3. Select the container that you want to use for this purpose

4. Click "Advanced proxy settings"

5. Enter the address. For example, `socks://us-nyc-wg-socks5-301.relays.mullvad.net:1080` if I'm using one of Mullvad's NYC servers

This supposes you're already connected to one of Mullvad's wireguard servers.

You can also use the FoxyProxy extension [0] for finer-control or extend this behavior across all tabs.

[0]: https://addons.mozilla.org/en-US/firefox/addon/foxyproxy-sta...