One handed smart phoes woes

I can't blame my doctor and therapists for these problems, had a flip phone back in '06'.
Normal people hold the phone in one hand and use the other for swiping, typing, etc. When I try to put it in my affected left hand, due to spasticity it either turns off the phone, adjusts the volume or turns on Bixby. I tried the ring attachment on the back of the phone, didn't work. Took 5-10 minutes to get the finger flat enough to insert. Then the spasticity of the thumb would curl over the screen, pushing whatever icons were there. And typing the left most letters just were not available or inserted where they weren't wanted.  The pop up button I didn't try but that makes the assumption that you can squeeze your middle fingers together as needed to stabilize the phone, never occur in my case. Neither of these works with the magnetic attachment I have for use in my car. 

So I do icon selection and typing with the right hand thumb. while holding the phone with my fingers. Which is a problem for items out of thumb range. I end up having to press the phone against my body and rotate it to get the thumb in position.