Sonos doesn’t make speakers for outdoors. They do sell outdoor speakers from a company called Sonance, which is too close of a name for comfort. In fact, Sonos has partnered with Sonance on their Architectural line (non-outdoors) to allow you to use the TruePlay function.
There’s not an easy way, IMHO, for you to resolve your issue. I’d be tempted to look in to an HDMI ARC enabled broadcaster of some type to get the signal from the TV’s ARC output to the Sonos Amp inside. But honestly, I’d be looking at almost any other solution first, my expectations of that working well are pretty low. Sonos just doesn’t make anything designed for your use case.
The other, more appealing way to attack this is to put an HDMI switch on the source, assuming the source is inside, and use the optical output from that switch to feed the Sonos optical to ARC adapter, plugged in to the Sonos Amp, and then run the long video portion of HDMI from the switch to the TV.