Hi Greg,
Digicamcontrol supports a multitude of camera models from Canon, Nikon, and Sony. It has an astromode, scripting etc... It says it supports the EOS R and the A7rii. I suspect it would also extend to the Ra and A7riii, but the software is free so try it.
Here's a list of supported cameras. There is also an associated forum for discussion.
http://digicamcontrol.com/cameras
Best
JA