I cannot find any way to get the "floating keyboard" to work in the iPad Playgrounds app. It's working fine for me in other applications such as Safari.
I'm using an iPad Pro 11".
I have tried the suggestions in the following question, the usual methods to float the keyboard simply have no effect.
When trying to "pinch" the full-size keyboard, it does nothing more than create key presses; holding down the "dismiss keyboard" button never shows the "Floating" pop-up.
Edit: I have found that when a number is selected, sometimes a "floating" numeric keypad will appear and it can be moved around.
But I still would like to get the full floating keyboard.