That's how I know that many people actually don't use smartphones as a phone, but as a replacement pocket computer and would rather communicate in other ways that the terminal would suffice.

If that's the case, why not actually target what you really want. It's not an UI, but a general purpose device that's terminal based mostly and has a keyboard. And then try to sell that to a niche within a niche.

Good luck with that.

Sorry, even as a prior life server administrator, being in the command line 100% of my day, even trying to answer an incoming phone call via terminal, no thanks.