Having done multiple trips like this… ill throw in my 2 cents.
I don’t have a CB… nor do I want one. There are much better things to purchase, even for car to car coms on the trail. FRS and MURS will satisfy all those requirements while providing much higher quality of communication than CB. I keep a case full of MURS radios just for others on the trail...
Plenty of places I didn’t have cellular, various parts camping and driving on road though CA Deserts, Oregon, Yellowstone. Plenty of observed dead spots in my travels, even near an interstate or road.
I do have a HAM radio, and on multiple occasions been my ONLY line of communication when adventuring. That said, there are even times when that wasn’t enough. Even if I could get into a repeater (Mendocino national forest) I needed a 50 watt mobile to do it. 5 watts off a handheld was useless. Lucky for me I have a crossband repeater capability in the truck so I was still able to talk to the truck, to talk to a repeater. Without it, if I was injured hiking, I would have been pretty screwed.
I think it’s worth mentioning I am a licensed HAM, and in order to really use this stuff you need a license. Yes, you can legally use one in a true emergency without a license, but having done this for 10+ years with really nice gear, it still takes practice.
You really do need to learn how to work the gear, setup your station, program and test repeaters to be effective at it, and in a new area, even that is challenging because there is no guarantee you are going to hit repeaters. Without taking the time to setup and test as you progress through your trip, it will probably be very hard for someone new to get help during a real emergency. Even near impossible if it was time sensitive / life threatening.
That leaves us with Sat Coms… The Iridium network is pretty awesome. InReach sat com 2-way communicator is a solid option. Ever since I learned about the Garmin mini and inReach, I was sold.
A Basic safety plan and a HAM radio is now part of my standard loadout when adventuring, off-roading, and camping. I love that it works stand-alone, but also works as a satellite modem when using a mobile device. Lots of convenience, ease of use, and reliability.
As much as I like HAM radio, the InReach is better for emergency stuff and family check-ins.