I made https://notionsmith.ai and technically it's "chat based", but the user isn't exposed to 99% of the chatting: the only chat interface on the site is there more as a bonus feature than anything.
On phones, I'd expect that voice will be a more popular input method than virtual keyboards.
I don’t know about you but freaking out all my fellow toileteers with loud phone conversations about my kinky exploits is one of the purest pleasures in life.
I regularly use speech-to-text transcription publicly. With my mouth close to the mic, I can speak softly enough that people outside of my personal space can't hear.
That being said, keyboards still have their place. Certainly, I use ChatGPT on my phone several times a week using keyboard input, and it's not particularly onerous.
Chatbot should be part of your ui instead of replacing the ui.