MrMobile on YouTube has a company that builds keyboard cases. They recently came out with a slide out keyboard case that works for any phone with Magsafe (or the newer Qi equivalent). https://clicks.tech/en/powerkeyboard

Personally, I think we could make touchscreen typing a lot better if we could move away from QWERTY. QWERTY is relatively better than Dvorak or Colemak on a touchscreen device. But we don't see a lot of innovation on the touchscreen keyboard layouts. One project I'm interested in is the Clearflow Keyboard layout (https://clearflowkeyboard.github.io/) which is already available on Gboard on Android. But there seems to be no way to try this out on iOS right now