How to make a bibliography with certain unused references?

Question

So im using biblatex with

\usepackage[style=apa, backend=biber, sortlocale=de]{biblatex}
\DeclareLanguageMapping{german}{german-apa}
\addbibresource{Literatur.bib}

For my paper I need to have two bibliographies. One for things I actually used in the paper and one for other potentially interesting articles and books for the topic that would be good for further reading but which I didnt actually cited or paraphrased anywhere.

I set it up like this:

\printbibliography[notkeyword={unused}, title={referenced stuff}]
\printbibliography[keyword={unused},title={Also interesting but not referenced stuff}]

But as references are only being put into the bibliography when I actually use them in the text somewhere, the unused stuff obviously won't show up.

Is there any way to tell latex to add those unused references?

I thought maybe there could be a way like

\begin{comment}
\cite{SomeUnusedArticle}
\end{comment}

So that I actually "use" the references in the document somewhere without them showing up in the compiled pdf's continous text and just appear in that second bibliography. Obviously the \begin{comment} way doesn't work as the compiler just ignores that entirely.

I ideally would like a solution that doesn't just put all unused references of the .bib file in that second bibliography, but particularly only those that have the keyword "unused" or are further specified by something else.

Any ideas?

Thanks!