How to create an alphabetical attachment list that supports unicode characters?

Question

I would like to be able to create a list of attachments similar to the list of figures or tables. However, since it makes little sense to sort the attachments by page number, I would like to sort them alphabetically.

I can create the list of attachments itself, but I'm having trouble sorting it alphabetically. I saw that it was possible to do it here. However, this solution does not work for me (with PdfLatex it works, but with LuaLatex, which I use, the classification is wrong):

So I was wondering if it was possible to use Lua directly or to use the power of Biber (outside the context of Biblatex) to alphabetize a list containing unicode characters. Wouldn't these tools be more efficient in this field?

Here is a MWE:

\documentclass{article}
\usepackage{hyperref, embedfile, hypgotoe, datatool}
\renewcommand*{\dtlsetUTFviiicharcode}[2]{%
    \ifstrequal{#1}{À}{#2=65\relax}%
        {\ifstrequal{#1}{É}{#2=69\relax}{\dtlsetdefaultUTFviiicharcode{#1}{#2}}}%
}
\makeatletter
\NewDocumentCommand{\declareattachedfile}{m m}{%
    \embedfile[ucfilespec={#2.pdf}]{#1}%
    \addtocontents{loaf}{%
            \protect\DTLnewrow{listofattachedfiles}%
            \protect\DTLnewdbentry{listofattachedfiles}{filename}{#1}%

            \protect\DTLnewdbentry{listofattachedfiles}{filetitle}{#2}%
    }%
}
\newcommand{\listofattachedfiles}{%
    \section{List of attached files}%
    \DTLnewdb{listofattachedfiles}%
    @starttoc{loaf}%
    \DTLsort{filetitle}{listofattachedfiles}%
    \DTLforeach{listofattachedfiles}{\theFiletitle=filetitle, \theFilename=filename}{%
        \vskip 12\p@ @plus\p@%
        \begingroup%
            \noindent\href[pdfnewwindow=true]{gotoe:embedded=\theFilename}{\theFiletitle}%
            \par%
        \endgroup%
    }%
    \newpage%
}
\makeatother
\declareattachedfile{example-image-letter-numbered.pdf}{Z}
\declareattachedfile{example-image-a4-numbered.pdf}{A}
\declareattachedfile{example-image.pdf}{1}
\declareattachedfile{example-image-a.pdf}{É}
\declareattachedfile{example-image-b.pdf}{N}
\begin{document}
\listofattachedfiles
Expected sorting :
\begin{itemize}
\item 1
\item A
\item É
\item N
\item Z
\end{itemize}
\end{document}