I know that this question has already been answered but I have found a simpler and cheaper way for anyone still struggling with this issue.
I brought an audio extractor off Amazon: 4K Audio Extractor HDMI by OREI
To make this all work, plug your source into the input and projector into the output, then plug the sound bar into the optical port. Make sure that in the projector settings the audio out device is set to AV receiver and the go to the sonos app and go though the “tv setup” after this you should be all good.
At time of this the audio extractor is only £44 which is cheap compared to others on the market.
I hope this helps :)
Moderator Note: Modified in accordance with the Community Code of Conduct. Replaced Hyperlink with product name.
@Dan346, welcome to the Sonos Community!
Thank you for sharing your experience using with us. I hope other users with this Epson EH-TW7000 project that want to connect it to Sonos find this helpful.