beorg 3.3.0+ comes with extensive support for external keyboards. To see the available keyboard shortcuts available at any point in the app hold down the ⌘ key on your keyboard.
If you are into customizing beorg then you can change any of the keyboard shortcuts below in your init.org. For example…
(define-key "tabbar" "s-a" ".agenda")
…will allow you to use ⌘-A to switch to the agenda tab instead of the default ⌘-1.
See library.org for a full list of scopes (in the above example “tabbar” is the scope") and actions (above “.agenda” is the action).