There is no reason a SiriusXM app couldn't be on a Hopper, but why? What is really gained? The Dot especially on sale is inexpensive and does so much more, why not get one and listen to any channel they have that way and all the free services. OR any number of other ways for no cost beyond an online subscription, from a Cell Phone via Bluetooth, from a Fire Stick or Fire TV, Roku, from a computer, etc.
The channels on DISH are a great plus particularly for those with no subscription. Having a subscription though once Alexa/Echo could connect to your subscription that's the number one way - want to listen to a baseball game? Just ask for the team and it finds it and plays it.
If anyone is thinking the app should be free meaning a "free" subscription- I am in no way in favor of that I want SiriusXM to be around for along time and if DISH has to pay I don't need my TV subscription to rise for a service I already have and pay for.