Swap left and right stereo channels in wireplumber

Alright sweet and simple, Edit: Wireplumber now uses .conf instead of .lua

1. wpctl status
2. Find your speakers and their id then run wpctl inspect id, replace id with the number
3. Copy the node.name value.
4. Create the below file at ~/.config/wireplumber/wireplumber.conf.d/alsa-speakers.conf

monitor.alsa.rules = [
  {
    matches = [
      {
        node.name = "~alsa_output.usb-ACTIONS_Pebble_V3-00.*"
      }
    ]
    actions = {
      update-props = {
        audio.position = ["FR", "FL"]
      }
    }
  }
]

Reboot your system and check that it worked by repeating steps 1-2 and look at audio.position.

TIP

Didn't work? Try node.nick or alsa.card_name instead of node.name

More information here