I have the qbittorrent web UI running in a separate container that’s attached to my gluetun container. I use the VPN_PORT_FORWARDING_UP_COMMAND option in my gluetun container:

    environment:
      - VPN_PORT_FORWARDING_UP_COMMAND=/bin/sh -c 'wget -O- --retry-connrefused --post-data "json={\"listen_port\":{{PORTS}}}" http://127.0.0.1:8072/api/v2/app/setPreferences 2>&1'

You may have to adjust the http://127.0.0.1:8072/ part based on your setup.

I’ve got an 8BitDo controller and while individual application support varies in quality (had some weirdness with Dolphin not playing nice), Steam consistently recognizes it just fine, literally plug n play. Any standard remappings I would typically do through Steam.

I’d used mine for a few years without issue, but recently had a thing where the controller stopped talking to the dongle. The only way i could use it was if i plugged it in. That required a windows executable to fix unfortunately, but the dongle does work again now. And to your point, I needed windows to remap the paddles on the back, but not the standard buttons.