A quick look through its documentation shows that it instructs the user how to go through a subset of the instructions the original user provided (or an alternative set of instructions if using Android 11+ as there it can use a different mechanism) plus a few more, in order to run a Shizuku service as user "adb".

From then on, that Shizuku service can then be used by other apps to do everything the "adb" user can, including installing and updating applications.

So I guess it could be used by something like F-Droid to go around Google's new mechanism to close down app installs.

For Android < 11 it's is no more non-expert friendly than the instructions already provided by the original user, though it's better in Android 11+ as there it's all interacting with menus on the Android side (see here under Start Shizuku)