TL/DR: 2017 Sony's can turn on/off with Google Assistant now.
So I've had a 2017 Sony Android Tv for awhile now and the Google Assistant's On and Off would never work. Matter of fact, I almost bought a Chromecast Ultra at one point, mainly just to turn on the TV, but realized it wasn't worth the hassle.
Well, last night while I was lamenting maybe buying a Samsung TV as my new living room TV, as I like how I can turn it off remotely via it's app.. I just half jokingly asked my Pixel phone's Google Assistant to turn on my Sony TV (like I had a million times before).... and the TV turned on! Startled, I asked it to turn it off, and it went off. Dazed and confused at what I just witnessed.. I decided to try to turn it on again.. and it came on! At this point, I was picking my jaw up off the floor... as a dream had come true for me (Maybe a Christmas miracle?). Anyway, what never worked before, suddenly works. Don't know if it was just me, or everyone.
So.. it seems an update happened at some point that allows this to work and I just didn't notice. Hence the reminder. You may be surprised to find out what didn't work before.. suddenly works today. Always worth the attempt. I came very close to making a buying decision I would have probably regretted, had I not checked again.
My Sony loses wifi every so often. Takes a hard reboot to fix. And I have about 20 devices in my house and nothing else has that problem. So it's definitely the TV.
Makes ok Google turn off the TV insanely unreliable.