There’s no way to do this without purchasing other Sonos hardware. If watching video on the PC, I would look at a Sonos HT Soundbar instead, perhaps with either HDMI-ARC, or Optical output, but it depends on the available connections on your PC - If your only option is ‘Bluetooth’ audio-out, then you’re going to need a Sonos product with a BT Rx, such as Era-100/300, Sonos Roam, or a Move 2 (now on pre-order). I would give the Move (gen1) a miss, as it’s BT link cannot be shared with other speakers, like your Sonos One SL.

Did the rep not tell you this?

I am using my sonos SL 1 stereo pair with Windows 11 through the apple music app (the new one, not itunes).  For some reason windows 11 does not let the connection happen directly but it is possible as evidenced by apple music.  I suspect that other applications will also support this wifi connection, have not tried plex for instance, but I am pretty sure that it does this as I could do it in windows 10.