I have used an Inreach Explorer for about six years now.
https://www.inreachcanada.com/
This unit allows not only emergency location service, but a plan can be selected that will allow it to be used as a communication device while out of cell service. It can be set up with select email addresses or with phone numbers for texting. The message length is limited to 160 characters. The advantage of this unit is that communication is two way whereas others are one way. You can also suspend the service for a minimal charge when you don't plan to be using it for a while.
It has been fairly reliable but I have had occasional messages that failed to reach intended recipients. Haven't had to use it for emergency yet. You can also select a plan that allows someone to track your position when you are out and about if you have the unit on. We have used it to follow our son on several long distance bike race epics, including mountain bike race from Banff south to the Mexican border.
I would recommend this unit for what you seem to want.