I don't have an unlimited plan on my phone, but wouldn't think navigation if used would take up all that much data?
It's kind of funny because my phone has like 12GB or RAM and nice video and all that (rivals a laptop, really) yet don't care to use it for much more than texting, phone (gasp) and some internet when away from the computer. Mostly WiFi though. Not too interested in apps in general, but do have a couple I use. Part of the allure of this particular unit for me was the ability to draw with its pen and also got a superblowout deal on it ~xmas 2020. Was happy with my S5, only the stupid usb port got messed up. Daughterboard was cheap, as were the easily replaceable batteries, etc. just didn't want to mess with it. Only reason I have this one.
Anyhow, point was that the hardware is more than capable but I would not be interested in using it for bluetooth (other than calls) or it needing to "run" while I drive. It goes in my pocket and stays there for the most part.
It is a nice option for most folks though to be able to so easily use and implement that technology of the pocket computers first, phone second appliance, haha.