It looks like more and More TVs are able to be controlled with HomeKit. Currently it looks like LG, Samsung, Sony and Vizio are going to be supported.
My Vizio TV just received a firmware update and now shows up in HA as a Homekit device, of course it cannot pair since TV types are not supported.
I do know that these TV brands do have other ways to be controlled and monitored by HA, but I have found the homekit controller to be a nice option for a few of my devices, and find it quite stable.
The exact features that are available vary from TV to TV. E.g. the LG implementation does not support reporting its play/paused/stopped state or sending the “stop” command.
Volume support is expected in future, but not going to make it into 0.107.x.
Not really something I’m likely to pick up, I don’t have a homekit TV and there is so much other stuff thats higher up my list, and not much free time.