I used to use a cell phone for conversations lasting an hour or more a day, held next to my head.
Where I commonly held the phone, I now have a scar where a basal cell carcinoma was removed.
I use the speakerphone, now.
I would frequently go over my 1500 min/mo plan back when Nokia was a thing, and all the way through the flip-phone days... Now, no doubt, the Droid I use is far more powerful... But I seldom actually carry the phone, interacting with it using a bluetooth mic/spkr earbud set...
I am currently playing with the idea of leaving the phone mostly in the truck, even when at home and in fact, most of the time... the phone itself tied to a head unit, boosting power and tied to a legit ground-planed antenna... The phone would still be capable of going portable for cases when I am not within bluetooth range of the truck, but really that is a small slice of actual time.
Two real problems limit this very fun project.
Firstly, I need to duplicate it for the mini van (which I actually use more)... That is problematic not only in the cost in both money and time (the head unit is my own, using raspberry tech), but in the interaction (and security) and ID, since I am getting the car tied into the local LAN when the car is home and the phone is active when the phone is within the car's matrix... That home-home scenario is beyond the phone's capabilities.
And more importantly, the AI in the phone simply is not reliable enough to interact exclusively via voice... ie: Google Assistant is just plain incapable of understanding redneck.

Even so, The tech is close to working in this fashion, and could be extended considerably utilizing internet, or even a low power transmission in realtime.. Say something around the same lines as a cordless housephone that could handle an intermediary range, greater than the range of bluetooth, but within say, 1/4 mile of the vehicle, at which point my particular needs are 98% resolved (when I am not in the woods). The car becomes the access point, and the device I have on me is a relatively low powered, low(er) frequency unit tying me to the capabilities residing in the vehicle.