I have two hands, but also have tendonitis in my right thumb, so I've been training myself to use my phone left handed. The first thing I tried was a smaller ph

I have two hands, but also have tendonitis in my right thumb, so I've been training myself to use my phone left handed. The first thing I tried was a smaller phone, but I'm also old and my eyes suck. Now I'm on a large phone (Note 8), and I'm not going back. The trick was to get a phone with (a) one-handed mode (entire UI shrinks to left side of screen), (b) a floating camera button (that I can position anywhere on the screen), and (c) a Lovehandle, or similar accessory, so I can confidently hold my phone in my left hand. Just some things to consider for your relative's needs.