Reliable way to patch a chapter in scrreport and article

Question

I need to run a command after each chapter, so I need to patch chapters. If I do:

\documentclass{scrreport} %% Works with memoir but not with scrreport

\NewDocumentCommand\MyAddLabel{}{\label{mylabel}}
\usepackage{etoolbox}

\makeatletter
%% Add the above command to \chapter if the command exists
\ifdef{\@chapter}{
  \ifpatchable*{\@chapter}{
    \apptocmd{\@chapter}{\MyAddLabel}{}{}%
  }{\PackageWarning{mypackage}{Chapters are not patchable.}{}}
}{}
\makeatother

\begin{document}
Test
\chapter{Testchap}
 asdf
\end{document}

Then it works great for the memoir class, but not for the scrreport class.

What's the proper way to also patch the memoir class in the scrreport class?

EDIT

The Komascript class even states:

Any package, that changes internal macros like \cs{@chapter}, \cs{@schapter}, \cs{@makechapterhead}, \cs{@makeschapterhead} is incompatible with \KOMAScript{} classes. Neither \KOMAScript{} nor the \KOMAScript{} author is responsible for this. Package authors are welcome to ask for interfaces they need, e.g., a good idea would be to define a own headings style.

EDIT2

I tried to use \AddtoDoHook{heading/endgroup}{\label{mydummylabel}} but it adds an ugly chapter or section text right after the section:

\documentclass{scrreport} %% Works with memoir but not with scrreport
\usepackage{lipsum}

\AddtoDoHook{heading/endgroup}{\label{mydummylabel}} % IRL, the label is programmatically chosen

\begin{document}
\lipsum[1]

\chapter{Here is my chapter}

\lipsum[1]

\section{Here is my section}

% \begin{thmE}
% Here is my important theorem  
% \end{thmE}

\end{document}

EDIT3

Oh, I understand, either we use heading/endgroup/chapter to target chapters, otherwise it calls the content like a macro:

\documentclass{scrreport} %% Works with memoir but not with scrreport
\usepackage{lipsum}
%%  Only for chapters
\AddtoDoHook{heading/endgroup/chapter}{Only for chapt.}

%% For everything
\def\mydummystuff#1{Coucou}
\AddtoDoHook{heading/endgroup}{\mydummystuff} % IRL, the label is programmatically chosen

\begin{document}

\lipsum[1]

\chapter{Here is my title}

\lipsum[1]

\section{Here is my section}

% \begin{thmE}
% Here is my important theorem  
% \end{thmE}

\end{document}

Answer 1

I solved my problem using hooks and a test to check if the class is KOMA:

\AddtoDoHook{heading/endgroup/chapter}{\pratendAddLabel}

With the test it looks like:

  \@ifundefined{KOMAClassName}{%
    % For articles/...
    \ifdef{\@chapter}{
      \ifpatchable*{\@chapter}{
        \apptocmd{\@chapter}{\pratendAddLabel}{}{}%
      }{\PackageWarning{proof-at-the-end}{Chapters are not patchable.}{}}
    }{}
    %% patch sections/subsections/paragraph/...
    %% https://tex.stackexchange.com/questions/631713/patch-section-command-fails/631717?noredirect=1#comment1575337_631717
    \ifdef{\@sect}{
      % \apptocmd{\section}{\pratendAddLabel}{}{}%
      \ifpatchable*{\@sect}{
        \apptocmd{\@sect}{\pratendAddLabel}{}{}%
      }{\PackageWarning{proof-at-the-end}{Sections are not patchable.}{}}
    }{}%
  }{%
    %% For KOMA classes/... or it won't work with scrreport
    %% \AddtoDoHook{heading/endgroup/chapter} is too specific 
    \AddtoDoHook{heading/endgroup/chapter}{\pratendAddLabel}%
    \AddtoDoHook{heading/endgroup/section}{\pratendAddLabel}%
  }%

Note that I just noticed that this code does not capture the section of a memoir… will need to read more doc!