Brand new Roku user here. Just bought the Roku Streaming Stick+, having never owned a Roku device before.
In my research prior to buying, I saw that this device can control external equipment via its remote (power and volume), so I assumed it will also be able to control my AV receiver.
The stick is plugged directly into one of the HDMI input ports on the back of the receiver. During the setup, it failed to detect and work with my receiver. It would play some music, but then it would ask me (three times) if the music has stopped (the music never stopped) and then said it can't control the "TV". I also tried selecting Onkyo from the list of brands, but that didn't help.
The HDMI RHID/CEC options are switched on in my receiver.
One of the uses for this stick will be to cast Spotify music from my smartphone to the receiver (where the video output to the TV isn't important). Ideally, I'd like it when I choose Roku Stick in the "Devices" section in Spotify on my smartphone, for the receiver to automatically turn ON (if not already ON), switch to the correct input and start playing music. This is what happens when I use Spotify with another receiver (also Onkyo, with built-in Chromecast) in my home.