I have a Garmin inreach, it requires a subscription (~$15/mo) and allows unlimited texts of three simple messages to a distribution list like "I'm resting", I'm moving", "I need help" at no cost, but for free-form, more descriptive messages, I believe you get 5 or 10 messages/month and get charged for additional over the monthly allotment.I thought about getting a Garmin Inreach, but I’ll wait for now to see if the service expands to Europe. I plan on getting the 15 PM to replace my 13 Pro next year!
For the Apple satellite, I suspect it is only used during emergencies since if I understand correctly, the iPhone user will communicate through a satellite to an emergency call center. So if I wanted to message my wife that "I am taking a break on my bike ride in the mountains and all is good", I don't know if the Satellite emergency response team would relay that to my wife or curtly tell me that this line is only for emergencies?