@Saltnvinegar Thanks for the note. Roku remotes that offer TV power and volume controls are not designed to directly control A/V receiver power or volume. The overall programmable functionality is limited to one TV/device programming at a time. See more here: https://support.roku.com/article/115013019828
If your TV and/or receiver that the device is connected to support HDMI CEC, and you have 1-touch play enabled on your device in Settings>System>Control other devices, you may be able to control A/V receiver power and volume via HDMI CEC when using your Roku remote, depending on the receiver/TV brand/model and supported functionality. (This may not work on every brand/model.)
Thanks,
Tanner