Hi. I don't know if i've found something bizarre here of if this is by design.
I have a Chromecast v3.
All4 have not released a TV App yet unlike every other provider.
You can sideload the phone app but you need an Airmouse style remote.
My wife found this by accident:
Hold the voice search button down
say: "play married at first site season 6 episode 13" (apologies about the content, I just know this one works)
Voila, All4 ident plays followed by the noted episode. If you use your phone to review names of content and say them prefixed with "play" it will mostly find the All4 content.
If you don't use the "play" prefix, it will do a general search, mostly coming back with All4 on YouTube.
Any idea how I'm searching and playing All4 content natively yet there's no app that can do it neatly?
Cheers,Michael D
Sure, All4 has been supported by the Google Assistant for the last 3 years. I thought you had to link your All4 account (I did it quite a while back, it's under "Videos" -- the same place you can link Netflix and Disney+), as described at https://www.channel4.com/4viewers/faq/enable-google-assistant , but maybe not.
From their FAQ, there are quite a few voice commands you can use:
You can also Cast to the Chromecast from the All4 phone app, which I usually find easier if I'm after a particular episode.