The workaround I ordinarily use for manually bringing up the on screen keyboard on Chrome OS (going to input methods and selecting emoji, then switching to keyboard) doesn't seem to work while in tablet mode. It seems that the on screen keyboard automatically suppresses itself if there is no input field detected, but only in tablet mode.

To reproduce:
1) In laptop mode on Pixelbook, start a Linux GUI text editor (e.g gedit under crostini)
2) Switch to tablet mode
3) Tap input methods, then the emoji button
4) Observe that no emoji keyboard pops up