This would be a great idea - using the Sonos Ace to properly calibrate TruePlay in the living room for the specific viewing position (instead of using the iPhone).

just this function would push me to buy a Sonos Ace.

Yea. This will push me to buy Sonos Ace as well. Lol. But this ideal will be great as the Sonos Ace will place exactly at our listening position and left and right channel can accurately listen and measure by Sonos Ace during the tuning. 

I fully agree even if in my case I am less worried about left and right (the 2 Era 300 are in symmetrical position) but rather better balancing btw the Arc (2 meters in front of me on a low TV cabinet) and the Era 300 (just behind the couch on stands at ear level). Also the front height and back channels would be better calibrated.

I'm on the fence about staying with Sonos, I love the devices but as an Android user I'm fed up with the inability to set up true play. I even bought an old ipad a few years ago but then support got dropped in the last update. I am intrigued by the Ace and bridging this gap for android users would encourage me to buy one and stick with Sonos next time I do a system upgrade. Really hope they do this. 

In my case TruePlay does not make a huge difference. In any case Android users are getting wireless lossless audio on Sonos Ace, while Apple users will not.

+1 “this function would push me to buy a Sonos Ace”