I was an a similar boat a few years ago, figuring out my options for maps and whatnot. My setup changed again this year, but I'll explain. Depending on how far you are into the Apple ecosystem, other options may make more sense.
Initially I had an Android tablet because they were cheap and included GPS. This worked for a couple years. I would hotspot it to my iPhone. I also had a DeLorme inReach Explorer (pre-Garmin). Gaia on Android back then was nowhere near as polished as it is on IOS. That got me interested in switching to an iPad.
Later I moved to an iPad Air with its own service plan. It's maybe $20 a month, you never have to fumble with hotspotting, and you wind up with independent/redundant devices. That has been great. Performance on whatever gen iPad I have is still okay, but the updates take so much storage that I have to uninstall everything whenever IOS needs to update. At some point, I'll upgrade to a newer iPad with additional storage space.
I bought an iPhone 15 Pro Max when it was released. The last couple of years I have been testing out its free included satellite texting capabilities. I found that it worked so well, I was comfortable dropping the inReach service and relying solely on the phone.
My opinion: the fewer steps you have to take to make something work, the better. Less for you to remember, and less to go wrong. My iPad sits in a dash mount, lives in the rig, stays plugged in and charged, and is ready to go as soon as I start the vehicle. I can run my navigation apps in civilization, Gaia/onX on the trail, stream music over bluetooth, etc. I know a lot of people like CarPlay, but it's nothing like having the full device at your fingertips.