Thanks to the separation of dots and base glyphs approach, Amiri font can be easily extended to cover all additional characters required for other Arabic script using language. For example, here are all Arabic Wikipedia logos set in Amiri:

It is still rough at edges, but things are improving. Since the font is getting more and more usable, brave souls can grab it from its github repository, no generated font is provided though, you need to build it from source using FontForge (this might be inconvenient, but I don't want to spread half done versions of the font).