It has the same issue described here https://forum.playcanvas.com/t/how-to-stop-canvas-resizing-when-mobile-keyboard-is-in-use/27882 . The canvas resizes once the virtual keyboard shows up. I think that in the most common use case the user doesn’t want the UI to change when the keyboard shows up. That’s why I ended up with a custom html page embedded in the PlayCanvas app via iframe, using custom CSS so that the keyboard wouldn’t change the layout of the page, but instead would just scroll to the input field.
No. iOS and Android have very different behaviours when the keyboard is on the screen and would make this near impossible to do for a full page app. Hence the comprise of a text input field at the (now) top.
It is possible with an embedded HTML at least. You can see the CSS I use on my last reply on that post, maybe something similar could be used/adapted on PlayCanvas as well?