I, during my free time, like to make games. I usually use the app, but on my school chromebook, I use EDU edition (found here). Said chromebook has a touchscreen. PICO-8 works until you touch it, and when you do so the mouse no longer works. This is what should be changed. It is incredibly annoying, because you have to save the file, reload the page, type load, find the file, and select it. It takes a while, and is annoying when your in the middle of something and just accidentally touch the screen (Such as when you are trying to point out something to another person), and I would love to see this changed. My solution? The little popup thing that says Sorry, touchscreen typing is not supported. Please plug in a keyboard! should have an extra button, 'Undo' (Or something, I'm not sure exactly what to call it). The button itself would then disable touchscreen mode.

I have run into the same problem. I have been teaching programming in school using Pico-8. The Chromebooks used in school have a touch screen. Once the kids touch the screen (of course they will!) they can no longer use track pad or the mouse, causing much confusion and frustration. It would be ideal if they can use both at the same time. If that's technically not possible, then an option in Pico-8 to not switch to touch mode would be great.
(PS: disabling the touch screen in Chrome altogether is not an option, since that would upset the school's IT support).