I am currently using PhpDocx 11 Advanced and it doesn't look possible to do a native conversion from docx to pdf without creating both a source and target file on the file system. There is a 'stream' option but in this version it only looks like it works for HTML output.
Is it possible to do this in PhpDocx 15, so the PDF output is streamed, and preferably the generated docx source too? I'm unable to try it out before paying for an upgrade as the conversion plugin is an Advanced feature.