I suspect many do. Just that this isn't a story about them.

As to the coverage: North American only. There is coverage in Canada and Puerto Rico.

The XM satellite are geostationary, the Sirius satellites are in a highly elliptical "tundra orbit" where they use apogee dwell over North America. ( https://en.wikipedia.org/wiki/Tundra_orbit )

SiriusXM is now only using the geostationary satellites.