Why is Fitness+ not available on desktop or laptop computers?

Is there really no way to watch the Fitness+ videos on my iMac? My only option is my iPhone, which is completely useless when you want to do choreographed routines. Am I supposed to hold my iPhone in my hand while doing this? If I prop my phone up somewhere, I can't see it.

I have a nice big screen right here on a desk that has lots of room in front of it for me to do a workout, but I can't use it for that.