LaTeX htlatex href using labels as ids

% About: https://tex.stackexchange.com/a/597771/242407
\documentclass{article}

\makeatletter
\expandafter\newif\csname ifishtml\endcsname

\@ifpackageloaded{tex4ht}{
    \ishtmltrue
}{
    \ishtmlfalse
}

\ifishtml
    % BEGIN Source: https://tex.stackexchange.com/questions/42927/converting-from-latex-to-html-using-htlatex
    \usepackage[dvips]{color,graphicx}
    \usepackage[tex4ht]{hyperref}
    % END

    \let\orig@section\section
    \renewcommand\section[1]{%
        \def\@sectiontitle{#1}%
        \futurelet\@aftersectioncommand\resolvesection
    }

    \def\writeSetHrefFallback{
        \write\@auxout{\protect\ifx\protect\sethrefaccessible\protect\undefined
            \protect\typeout{HTMLLabels: Fallback was used!}
            \protect\def\protect\sethrefaccessible \string##1{}
            \protect\fi}%
    }

    \def\hrefaccessible{}

    \def\sethrefaccessible#1{
        \expandafter\global\expandafter\let\csname hrefaccessible@#1\endcsname\hrefaccessible
    }

    \def\resolvesection{%
        \let\@storedlabel\relax
        \ifx\@aftersectioncommand\label
            \typeout{HTMLLabels: Section followed by label}%
            \let\orig@label\label
            \def\label##1{%
                \def\@storedlabel{##1}%
                \def\curhypid{##1}%
                \write\@auxout{\protect\sethrefaccessible{##1}}%
                \let\label\orig@label
                \expandafter\orig@section\expandafter{\@sectiontitle}%
                \label{##1}%
            }%
        \else
            \let\curhypid\relax
            \typeout{HTMLLabels: Section not followed by label}%
            %
            \expandafter\orig@section\expandafter{\@sectiontitle}%
        \fi
    }

    \let\orig@ref\ref
    \newcommand\htmllabelref[1]{%
        \typeout{HTMLLabels: For #1: \expandafter\meaning\csname hrefaccessible@#1\endcsname}
        \expandafter\ifx\csname hrefaccessible@#1\endcsname\hrefaccessible
            \begingroup
            \def\rEfLiNK##1##2{##2}%
            \Link{#1}{}%
            \orig@ref{#1}%
            \EndLink
            \endgroup
        \else
            \orig@ref{#1}%
        \fi
    }
\else
    \usepackage[pdftex]{color,graphicx}
    \usepackage[margin=2.5cm,a4paper]{geometry}
    \usepackage{hyperref}
\fi

\makeatother

\begin{document}

\makeatletter
\ifishtml
    \writeSetHrefFallback

    \LinkCommand\HeaderTarget{div,href,id}

    \def\curhypid{sec:unknown}

    \Configure{section}
    {}{}
    {%
    \HCode{<h3>}
    \ifx\curhypid\relax
        \PackageWarning{HTMLLabels}{Section misses label!}
    \else
        \HeaderTarget{}{\curhypid}\EndHeaderTarget
    \fi
    \TitleMark\space}
    {\HCode{</h3>}}

    \ConfigureMark{section}{\thesection}
    \def\ref{\htmllabelref}

    \let\orig@T@ref\T@ref
    \def\alt@T@ref#1{%
        \let\T@ref\orig@T@ref
        \htmllabelref{#1}%
        \let\T@ref\alt@T@ref
    }
    \let\T@ref\alt@T@ref
\fi
\makeatother

Lorem ipsum dolor sit amet, \ref{sec:further} (label does not follow section `Further heading' immediately:
falls back to using the autogenerated id instead),
consectetur adipiscing elit. Curabitur fringilla semper leo fringilla
varius. Etiam nunc dolor, consequat elementum malesuada facilisis, rutrum ac massa. Maecenas et
cursus libero. Maecenas tincidunt mattis hendrerit. Maecenas vitae accumsan est, id mattis mauris.
Maecenas et massa sed tellus efficitur rutrum id a mauris. Etiam velit mi, pellentesque vitae
tincidunt at, pharetra eget arcu. Nulla venenatis pulvinar dignissim.

Ut justo libero, pellentesque at fermentum mollis, tristique at tortor. Pellentesque ac nisi ligula.
Quisque in lectus in dolor tempus pretium. Suspendisse placerat aliquam mauris, et porttitor tellus
finibus id. Morbi ut nibh nisi.

Mauris fringilla bibendum dui eu vestibulum. Curabitur hendrerit, velit vitae pellentesque semper,
sem neque molestie metus, ut tristique odio quam auctor enim. Nulla tortor mauris, posuere vel
sagittis id, bibendum in nulla. Donec et sapien sit amet neque vestibulum fermentum. Maecenas lorem
lectus, convallis ac ornare eu, viverra quis justo. Donec aliquam aliquet libero et lacinia. Nullam
iaculis ligula interdum, imperdiet justo vitae, vehicula augue. Nam eu leo vitae dui gravida egestas
ut sagittis purus. Aenean porta, nisi et tempus elementum, sapien ante sagittis arcu, non aliquam
elit quam vestibulum felis. Phasellus et mauris facilisis, fringilla risus eu, iaculis dolor.

Fusce malesuada accumsan erat in tempor. Fusce in condimentum odio. Etiam quam sem, auctor vitae
ante eu, laoreet pharetra metus. Duis eget libero quis diam malesuada venenatis. Duis sit amet nisl
mauris.

\section{Section heading}\label{sec:intro}

Blah blah blah blah blah blah blah blah blah blah blah blah blah blah
blah blah blah blah blah blah blah blah blah blah blah blah blah blah
blah blah blah blah blah blah.  Here is a citation\,\cite{EXAMPLE}.

Blah blah blah blah blah blah blah blah blah blah blah blah blah blah
blah blah blah blah blah blah blah blah blah blah blah blah blah blah
blah blah blah blah blah blah.

This is a test to link to Section this text is for searching in HTML Karen heading
\ref{sec:intro}.

% Don't do it like this! \label should follow \section{} immediately
\section{Further heading}

\label{sec:further}

\end{document}