Taking coordinates of Test.pos file type not possible!

1. Test.tex

Running Test.tex (see below) saves the coordinates (as pt, not mm or sp) of

eins{title 1}{some text }

in the file Test.pos, which is:

% this is Test.tex

    documentclass{article}
    usepackage[paperwidth=210 mm,paperheight=297 mm,textheight=0mm,left=30mm,right=0mm,top=40mm,bottom=0mm]{geometry}
    topskip=0pt 
    setlength{parindent}{0pt}
    
    usepackage{zref-abspos} 

%%%%%%%%%%%%%%%%%%%%%%  Producing .pos file %%%%%%%%%%%%%%%%%%%%%%%%%
newwritemywrite
immediateopenoutmywrite=jobname.posrelax 
newcommand{eins}[2]%
{zsavepos{#1}
    {#2}% Output the text provided as mandatory argumentm
    immediatewritemywrite{withoutpt{thedimexpr zposx{#1}sp relax},withoutpt{thedimexpr zposy{#1}sp relax}}% 
}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%% makes the output in .pos without pt %%%%%%%%%%%%%%%%%
makeatletter
newcommandwithoutpt[1]{%
    strip@ptdimexpr dimexpr#1relaxrelax
}
makeatother
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


begin{document}


eins{title 1}{some text }


end{document}

2. Testtt.tex

Testtt.tex takes the pdf "blabla.pdf" and puts "some new text…" to the coordinates (10,20) (in pt)

% this is Testtt.tex

documentclass{article}
usepackage[paperwidth=210 mm,paperheight=297 mm,textheight=0mm,left=30mm,right=0mm,top=40mm,bottom=0mm]{geometry}
topskip=0pt 
setlength{parindent}{0pt} 


begin{document} 
    includepdf[
    picturecommand*={
        put(10,20){some new text for the coordinates in Test.pos}%
    }]{blabla.pdf}
end{document}

However if I change

put(10,20)

to

put(input{Test.pos})

It doesnt work. So it doesnt take the coordinates in Test.pos.

Doe someone have an idea? Thanks for helping!