Some Roku devices, such as Roku TVs, also support:
VolumeDown
VolumeMute
VolumeUp
PowerOff
Roku TV devices also support changing the channel when watching the TV tuner input:
ChannelUp
ChannelDown
Roku TV devices also support keys to set the current TV input UI: InputTuner
InputHDMI1
InputHDMI2
InputHDMI3
InputHDMI4
InputAV1