D does technically run on all three of those platforms (ios, android, wasm). Of the three, android is probably the most mature. Wasm is not very usable, because wasm itself doesn't yet have a garbage collector, so the d runtime is not ported. For iOS, there is a fork of GDC (GCC-based compiler) which is supposed to run, but there isn't very much interest in it. If you put in the work, you could likely get all three to work, but there's nothing OOTB yet.