Question

Is it possible to import symbols or shapes from dia's SVG format?

Answer 1

Yes, please see How can I use my own node symbols in yEd?

Comments

I don't think this answer addresses the question.  Dia uses their own wrapper around a SVG file, called a .shape file.  They also have other meta data in this shape file that's not SVG specific.  Perhaps someone has a script that can convert them?

---

Dia supports export to SVG. Open your *.shape file in Dia, then export to SVG, then follow the instructions in How can I use my own node symbols in yEd?