How to surround a theorem/definition environment with a rectangle that has a TikZ picture in the corner?

Question

In another question user campa showed how to use TikZ to draw a certain picture (an adaptation of the Bourbaki dangerous bend symbol).

How can I draw a rectangle around a theorem/definition/etc. environment that has campa's picture at the top left corner?

I'd like to be able to achieve this using code similar to the following:

\documentclass{scrartcl}
\newtheorem{theorem}{Theorem}
\usepackage{lipsum}
\begin{document}
\begin{mydangerenv}[A]
\begin{theorem}
\lipsum[1]
\end{theorem}
\end{mydangerenv}
\end{document}

Answer 1

Here is a tcolorbox-based attempt:

\documentclass{scrartcl}
\newtheorem{theorem}{Theorem}
\usepackage{lipsum}
\usepackage[most]{tcolorbox}
\usepackage{tikz}
% Definition of \mydangersymbol taken from: https://tex.stackexchange.com/a/604048/134144
\newcommand{\mydangersymbol}[1]{%
      \begin{tikzpicture}[baseline=(x.base)]
         \draw[rounded corners=.01em] (-.05em,-1.3em)rectangle(.05em,.9em);
         \draw[fill=white,rounded corners=1] (0,.8em)--(.8em,0)--(0,-.8em)--(-.8em,0)--cycle;
         \drawvery thick,line cap=round--(.3em,-1.3em);
         \node(x) at (0,0em) {\normalfont\sffamily\small#1};
      \end{tikzpicture}%
}
\NewTColorBox{mydangerenv}{+O{}}{%
    enhanced,
    sharp corners, 
    colback=white,
    coltitle=black,
    title={\mydangersymbol{#1}},
    attach boxed title to top left ={yshift=-\tcboxedtitleheight/2-4pt,
                                     yshifttext=-\tcboxedtitleheight/2-4pt, 
                                     xshift=-\tcboxedtitlewidth/2+0.25mm},
    boxed title style={colback=white,
                       colframe=white, 
                       sharp corners, 
                       boxsep=0pt, 
                       boxrule=0pt, 
                       bottom=3pt, 
                       halign title=flush center},
  boxrule=0.5mm,
  top=-\tcboxedtitleheight/2+5pt,
  boxsep=5pt,
  }
\begin{document}
\begin{mydangerenv}[A]
\begin{theorem}
\lipsum[1]
\end{theorem}
\end{mydangerenv}
\end{document}