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

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.