Hi. I’ve decided to create my new home theatre with Beam 2, 2 Sonos 100s and Sub mini. My audio and video sources is AppleTv 4k and I use FHD projector. So obviously my Beam is on on side of the room where the projector is casting the image and the projector is on the outset side (circa 7 m / 22 ft away). 
Im to make it all work I read and watched few suggestions that I must use an HDMI matrix/splitter as my projector won’t allow me to use eARC. So I bought devices like EZCoo Model：EZ-SP22H2EARCO or its brother EZ-SW21H21A-EO. The challenge I see is while I connect it all together to test with short (eg 2-3 meter HDMI like the white one from Sonos box) it does play Dolby Atmos movies and music from AppleTv. When I then connect it all as it should be with a long HDMI cable (15 m/50 ft) across the room it doesn’t recognize the signal (I guess as eARC) and plays only Dolby Digital or Multichannel PCM. 
So I know that now with new iOS 18.x you can Airplay 2 with Dolby Atmos too. 
nie I wonder, it doesn’t recognize play it for me, I see it on AppleTV but I can’t control it from Sonos app. The ultimate question would be how the Airplay 2 Dolby Atmos compare to the HDMI eARC version? Should I strive to find the way to fix tmy wire setup or give up on it and  be satisfied with the Dolby Atmos via Airplay 2?