I am sorry, but that is absolutely typical demand, I have never seen at least one printing house which does not demand that... (And this is not a solution! :o))

In nowadays it is the client who choose the specific printing office, my situation is the same.

That printing house demands expecially this:

PDF file must be version 1.3

Embed the typeface in the document along with the image data. Avoid using OPI commentaries! The typefaces used may be of the following standards: Type1, TrueType, and Opentype. As a matter of principle, the data is provided as a composite (not separated). Formats other than PDF are accepted only after prior agreement.

The PDF provided file should especially not contain any kind of meta-information, hypertext link, etc.

Everyone in printing industry knows what does it mean "to embed fonts", it is similar like when somebody wants pdf x-1a file (in printing industry the standard).

I am not a programmer, I don't know what does it mean in a code point of view. Trust me, embedding of fonts is the standard ("if you are not able to provide us the file as we need, your client should find another typesetter" - who typesets in InDesign). InDesign subsets typically just fonts used for texts where is not used 100 % of alphabet (pdf export settings).

Honza

P. S. Some inspiration could maybe provide the Scribus, it has nice pdf export possibilities, better than InDesign itself!
P. P. S. I have sent this to Hans and after that found your answers here, so I am sending similar info.