ENable modifier and function keys in on-screen keyboard

I'm using Ubuntu on a touch-only x86 tablet (Lenovo Miix 8 2), and my only recourse for input is touch and touch keyboard.

The touch keyboard doesn't display modifiers (Ctrl, Alt, Insert, Arrows, etc) or function keys (F1, F2, F3 etc). Is there a way to enable full keyboard layouts like Windows 10 does?

Additionally, is there a way to have the OSK provide feedback as to which key you are pressing? Not having some visual indicator of the key being pressed makes it almost impossible to type passwords into terminals without having to deliberately and slowly press each key, and not without several retries.