So while traveling last week, my brother used the voice search feature in YouTube on our Roku Stick+ and it worked. Surprised the heck out of me. I was looking forward to that feature for a long time. Glad to see it finally works.
When we got home, I tried using the feature on my Roku Ultra (4640X) running version 9.2 and it did NOT work (as of 2/11/2020). Interestingly enough, when I tried to use it, it said "Sorry, that's not yet supported". Don't know if there's any significance to the "yet" part. I hope so, and soon.
I don't know what other Roku devices support voice search in YouTube. If others can chime in, that would be useful for all. Maybe the newer Roku Ultra (4670)?
Roku Ultra 4660RW, 9.2.0. Voice search has been working well, have had it for 12 months and was last working less than a week ago when used. 02/12/2020 and voice search just says "sorry, that's not yet supported." to all searches. A reboot and a repairing of the remote hasn't resolved. Maybe the feature is offline at Roku?
I received a notification when I perform a search on the youtube app that the voice search option is available on the phone app and it will link the search to the roku app. Perhaps they needed to work on some issues with the feature.
It does appear that youtube reinstalled the "press for more options" feature on the app.
Do you know the format for the voice commands?
Does it just work with the search for content or can you actually do things, like change channels?