It wouldn’t work well. For TV sound there is a timing offset between grouped players and the Arc (or any other Sonos home theatre player).
On screen the gun would fire, the crack would come from the Arc, then a split second later the boom would emerge from the sub.
Also, keeping the volume levels in step would be awkward. A TV remote would only affect the Arc. You would have to keep a Sonos controller app to hand.
Further, the Arc wouldn’t apply a crossover to direct the lower frequencies to your sub. It would still try and reproduce the full range itself, including the LFE/.1 channel.
Not a good idea at all.