We had OnStar service for 5 years provided by our dealer when we purchased the truck. We didn’t use many of the OnStar services.
We did take advantage of the initial offering of their unlimited data plan at $15 a month. It was mostly just okay but occasionally very useful.
Supposedly we were “grandfathered” into the data plan at $15 but when our dealer provided OnStar subscription expired they accidentally cancelled our data plan as well. I spent hours on the phone trying to get it reinstated. Everyone I spoke to agreed that it shouldn’t have been cancelled and we should get the $15 plan but no one could do anything because the plan was no longer in their system. My experience dealing with OnStar customer service led me to conclude that I didn’t want to deal with them in the future.
For emergencies I carry a Garmin InReach. I’ve also thought about an Apple Watch for crash detection but haven’t followed through on that yet.