Granularity! We have granularity. 
A friend of mine who uses switch control mentioned that harmony activities can go down to the granular level (pause, play after Pause, Rewind etc) but you have to put them in as a “step” in the activity. And the trick I hadn’t realized is that you have to also include whatever device controls the power for your home entertainment system. Otherwise switching to the granular activity will shut down the TV.
So, I have now been adding individual activities Basically to represent individual button pushes on the handheld remote. Once I have an activity set up the way I want, so that selecting it in the harmony app would create the effect I want, I can then associated with a virtual switch, and in turn have echo flip that switch with a voice command.
So I now have a harmony activity called “halt Roku” which is the same as hitting the pause button on the remote. And another Harmony which is the same as hitting the play button to restart it… This activity includes my TV and my Roku as entertainment devices. It has a “step” in the starting sequence that uses the pause command on the Roku.
No commands are issued for the TV, which is what confused me the first time through. Also, I do not use a “channel” for the Roku. I want the Roku to stay where it is, just hit the pause.
Also, I don’t know if I’m just doing this wrong, but I found I had to first create the activity with the devices, and then go back in and “edit the devices” in order to add the steps. If someone knows of a way to add the steps on the first pass through, please let us know.
Anyway, once I had the activity set up and working, I assigned A virtual switch called “halt”, did the usual echo authorization, and if I say “Alexa, turn on Halt” the Roku pauses!
The tricky thing is finding phrases I can remember that are not the same as commands that echo has reserved for its own uses. That’s why I can’t use “pause” or “stop.”
But I now have total hands-free control for almost every button on the Harmony remote!
This is obviously not as smooth or easy to remember as “turn on Roku” or “turn on Netflix”. I expect a lot of able-bodied people won’t want to bother with it. But for others with limited hand function, this is seriously very cool. 
