Currently, I don't think there is any way to use a keyboard shortcut to directly open a sidebar tab ("Properties", "Page", "Styles", "Navigator") directly.
The exception to the above is "Styles" - there is an option in the "Functions" list in the "Customise" -> "Keyboard" dialog to set a shortcut that actually opens the sidebar's "Styles" tab. Pressing the keyboard shortcut again actually closes (toggles) the sidebar, which is the behaviour I would expect from this keyboard shortcut.
However, this does not seem to be possible with the rest of the sidebar's panels (Properties, Navigator, etc). Unless I am missing something, there is no way to open the sidebar directly on the "Properties" tab. This would be convenient to avoid having to click to switch from e.g. the "Styles" tab or whichever tab was used last. This shortcut should also toggle the sidebar when pressed again, like the "Styles" shortcut does.
If this is currently somehow possible, then it is not readily apparent from the Keyboard customisation dialog box, which means that the descriptions are not intuitive (they should be somehow associated with the sidebar).
In addition, the keyboard shortcut to open the navigator (default F5) actually opens a separate, undocked dialog box for the navigator. It should toggle the relevant view from the sidebar instead (whether docked or undocked, just like "Sidebar" keyboard shortcut does. As it stands, we have the very confusing case where you can have a navigator open from the sidebar and a separate undocked navigator window simultaneously.
*** This bug has been marked as a duplicate of bug 84502 ***