@MrObvious welcome to the forum.
Not sure if this is quite what you are after but if you follow the instructions in this post you can add a plugin to Joplin which adds two buttons to the top right toolbar.
(1) closes / opens the Notebook pane (like F10) and (2) opens / closes the note list (like F11).
I have found this useful when already using the mouse and scrolling through notes as it is just a mouse movement and click to get some more screen space.
Maybe someone knows how to modify this so that one button opens and closes both?