Writing something takes more work than not writing something, but I never used the word 'expensive'.  I definitely think a there should be a tkinter-based pip gui.  Since there would be no needed interaction with IDLE internals, it should be a stand-alone module run in a separate process.  (The difference from a dependent module is trivial -- use Tk rather than Toplevel for the main window and add root.mainloop().)

It occurs to me today that the gui should not necessarily be tied to working with site-packages for a particular version of Python but could be based on a ttk Notebook with a tab for each installed version of Python.  (I assumes that discovery method of py can be reused or extended.)  That should make it easy to compare what is installed for different versions and to copy a set of packages to a new version.

As for magical syntax: I believe Guido has vetoed that idea as part of his admonishment that IDLE should not compete with IPython, PyCharm, etc.  In any case, Shell's visible input syntax so far been limited to the Python syntax of the console interpreter.  I am not inclined to change this. On Windows, IDLE's Shell effectively replaces the console interpreter for many users.

Adding a System Shell option to the run menu is a separate issue, which I have added to my private list.  Making the console easier to access would not solve all the problems of using pip directly and would not have the added benefits of a visual display.