Platform support?

[JN via Digitalmars-d]

I'm curious about something. What platforms exactly are supported 
by D? It's hard to find concrete data, and if anything it's all 
hidden in forum posts.

Obviously Windows, Linux and macOS have good support. But what 
about mobiles? Android, iOS? Is it more like:

- not supported at all
- hello world works
- most stuff works and you can interface with native OS APIs 
(Android NDK libraries etc.) ?

How about Emscripten/WebAssembly?