This post has some links to the underlying libraries that the map uses.
You can see if you look through those that the icon property for the mark accepts any generic url. The oh-mapmarkerhas been wrapped to also accept oh icons, but you should still be able to seticon` to any viable url.
So, if you put the icons you want in html in your conf folder, then you can use the /static/nameOfIconFile url to access it.