we had a 21 yukon with the rear media....using a samsung galaxy s20+ we were able to screen share straight to the RES fairly consistently. i simply used the "smart view" function which is essentially android's own screen share app (your pixel 6 should probably have that o it...pull the screen down twice and it's usually in the second group of apps.
every now and then there'd be a hiccup connecting but in general, it was fairly reliable sharing the phone to the screens. definitely could try a 3rd party app if need be
if i remember correctly someone in the back seat had to click "miracast" first on one of the screens...then we'd access the screen share app on our phone...and go from there