Tikz "overlay" option does not draw nodes referencing local bounding box

Question

I'm wanting to populate the cover page of my package with a border of examples of my package command's outputs, which are drawn in TikZ. To this end I'm using a tikzpicture environment with the overlay option. However, part of my command's syntax involves defining a local bounding box and using its anchors to draw other parts of the symbol, similar to the MWE below:

\documentclass[a4paper]{article}
\usepackage{tikz}
\begin{document}    

\begin{tikzpicture}[overlay]

\begin{scope} [local bounding box=M]
\draw (0, 0) rectangle (1, 1);
\end{scope}
\node [anchor=east] at (M.north west) {A};
\end{tikzpicture}

\end{document}

However, when I compile only the rectangle renders, the 'A' node does not:

When I compile with the overlay option removed, the node renders:

Is it possible to get the node to render even when the overlay option is set?

Answer 1

overlay stops the bounding box calculations (use as bounding box would do it too).

Instead of overlay you could reset the bounding box at the end:

\documentclass[a4paper]{article}
\usepackage{tikz}
\begin{document}

\begin{tikzpicture}    
\begin{scope} [local bounding box=M]
\draw (0, 0) rectangle (1, 1);
\end{scope}
\node [anchor=east] at (M.north west) {A};
\pgfresetboundingbox
\path[use as bounding box] (0,0);
\end{tikzpicture}

\end{document}

Answer 2

I know that we have to avoid nested tikzpictures, but this is the only way I found:

\documentclass[a4paper]{article}
\usepackage{tikz}
\begin{document}    

\begin{tikzpicture}[overlay]
\begin{tikzpicture}
  \begin{scope}[local bounding box=m]
  \draw(0, 0) rectangle (1, 1) coordinate (M);
  \end{scope}
  \begin{scope}[overlay]
  \node [anchor=east] at (m.north west) {A};
  \end{scope}
\end{tikzpicture}
\end{tikzpicture}

I tested it and works... But may be is not the suggested way.

PS: You can imagine the way I thought to trick the environment :P