If you can’t use a phone with your hands, then Apple’s Switch Control could be a possible answer. You use a switch to access every function of the phone. (A switch is a binary input device - it can be any kind of thing really.) I use a Buddy Button but you can use head movements or clickers or sip puff etc. Usually the “accessibility” options are a limited subset of the functions available to everyone else, but Apple have opened up everything to disabled users. Everything an able-bodied person can do with their iPhone, a quadriplegic can do as well.
NOTE: Switch Control isn’t just available on iOS devices, it’s on all kinds of Macs. That means you can control your iPhone, laptop, iMac, Mac Mini or any other Apple device with a single switch like the Buddy Button and a Bluetooth bridge like the Tecla.
I know this sounds like an advert for Apple, but they really are world leaders at this stuff and I haven’t found any other company that does it as well as this out-of-the-box. Certainly not Android and Microsoft, and I’ve tried both over the course of a decade and Apple are far and away the best. Once an able-bodied person has helped you set it up for five minutes, you will probably never need them to help you again. Unless you drop it. Obviously.
Toolchain series tip!