Introduce .bib-file data directly into Latex documentation using \bibcitem{citekey}

bibtex_documentation.sty

\usepackage{listings}
\usepackage{xcolor}

\let\oldaddbibresource\addbibresource
\renewcommand{\addbibresource}[1]{%
  \oldaddbibresource{#1}%
  \expandafter\newcommand\csname thebibfile\endcsname{#1}%
}

% \makeatletter
% \patchcmd{\lst@Init}{\par\penalty -50\relax}{\relax}
% \makeatother

% adapted from the impressive biblatex-sbl package
\lstdefinelanguage{BibTeX}{%
  % keywordsprefix={@}%
  keywords={%
    @ancienttext,@article,@book,@bookinbook,@classictext,@collection,%
    @commentary,@conferencepaper,@inbook,@incollection,@incommentary,%
    @inlexicon,@inreference,@lexicon,@manual,@misc,@mlasource,@mvbook,%
    @mvcollection,@mvcommentary,@mvlexicon,@mvreference,@online,@reference,%
    @review,@seminarpaper,@series,@suppbook,@thesis,@unpublished
  },
  emph={%
    addendum,address,author,bookauthor,bookeditor,booktitle,chapter,crossref,%
    date,datea,doi,edition,editor,editora,editoratype,editorb,editorbtype,%
    editorc,editorctype,editortype,entrysubtype,eprint,eprintclass,eprintdate,%
    eprinttype,eventdate,eventtitle,institution,issue,issuetitle,journal,%
    journaltitle,location,maineditor,maintitle,maintranslator,nameaddon,note,%
    number,options,origdate,origlanguage,origlocation,origpublisher,origyear,%
    pages,part,preface,publisher,publishera,pubstate,related,relatedoptions,%
    relatedtype,revdauthor,revdeditor,revdtitle,series,seriesseries,%
    shortauthor,shorthand,shortjournal,shortmaintitle,shortseries,shorttitle,%
    sorttitle,subtitle,supplemental,title,titlea,titleaddon,titletype,%
    translator,type,type,url,urldate,venue,version,versiona,versionb,volume,%
    volumes,witheditor,witheditortype,withtranslator,withtranslatortype,xref,%
    year%
  },
  sensitive=false,
  breaklines=true,
  breakatwhitespace=true,
  morecomment=[l][basicstyle]{=\ \{}
}

\lstset{%
 language=BibTeX,
 backgroundcolor=\color{gray!5},
 basicstyle=\ttfamily\small,
 keywordstyle=\color{teal},
 emphstyle=\color{purple}
}

\lstset{rangeprefix=\%\[\[\ ,% percent + double left square brace + space 
        rangesuffix=\ \]\]}% space + double right square bracket

\newcommand{\bibcitem}[1]{\lstinputlisting[linerange=#1-end,includerangemarker=false,breaklines=true,postbreak=\mbox{\textcolor{gray}{$\hookrightarrow$}\space} ]{\thebibfile}\nocite{#1}}