Well as an alternative method, i used a CUPS PDF printer ( https://www.cups-pdf.de/ ) and I changed the ghostscript prams adding " -dSubsetFonts=false " to the default command.
Now the command is
GSCall %s -q -dCompatibilityLevel=%s -dNOPAUSE -dBATCH -dSAFER -sDEVICE=pdfwrite -sOutputFile="%s" -dAutoRotatePages=/PageByPage -dAutoFilterColorImages=false -dColorImageFilter=/FlateEncode -dPDFSETTINGS=/prepress -dSubsetFonts=false -c -f %s
After this modification, printing on the PDF printer shows that the fonts are fulli embedded (the “sub” column with value “no”)
mirto@bianco500:~/APPOGGIO$ pdffonts hosepla_book.odt__le-job_216.pdf
name type encoding emb sub uni object ID
------------------------------------ ----------------- ---------------- --- --- --- ---------
LiberationSans-Bold~6ae TrueType WinAnsi yes no yes 7 0
LiberationSans~6af TrueType WinAnsi yes no yes 9 0
LiberationSerif~6b0 TrueType WinAnsi yes no yes 15 0
LiberationSerif-Bold~6b1 TrueType WinAnsi yes no yes 21 0
LiberationSerif-Italic~6b2 TrueType WinAnsi yes no yes 24 0
[none] Type 3 Custom yes no no 42 0
LiberationMono-Bold~6ac TrueType WinAnsi yes no yes 60 0
LiberationMono~6b3 TrueType WinAnsi yes no yes 58 0
[none] Type 3 Custom yes no no 391 0
DejaVuSansMono~6ad TrueType Custom yes no yes 392 0
[none] Type 3 Custom yes no no 439 0
[none] Type 3 Custom yes no no 506 0
[none] Type 3 Custom yes no no 536 0
[none] Type 3 Custom yes no no 592 0
mirto@bianco500:~/APPOGGIO$
It should be wonderful if we can change the gs parameters in Writer