[o40]

Braille input exists on apple phones:

https://support.apple.com/en-us/HT210066

and I think Android supports something similar.

[puzzlingcaptcha]

Of course, but you generally need to hold the phone with the screen facing down (as you are supposedly hard of seeing, e.g. https://youtu.be/wueLXCbm_KY?t=45). Here you could have a touchscreen or tactile buttons seamlessly integrated on the back of the device.