But the panel is always docked to the current lister, I then have to click on the float button on the panel.
Interestingly enough I noticed the panels float button's tooltip says alt+f but attempting to use it focuses the menu bar. I tried to find the source of this hotkey in the "Customize..." window and could not find it.
I set up a dedicated lister layout plus a hotkey that either opens it or sends it to the foreground.
No tree view, minimal menus and the actual file view as small as possible (its content is irrelavant):