embedded-hal

If you want to get something done with microcontrollers, ARM Cortex-M tends to be much more powerful and is already great fun to write Rust for. It's a bit of work to get started--certainly a lot compared to Arduino which abstracts away even things that shouldn't be--but the code can be much more readable and portable than the corresponding C. For example, get this $2 board http://wiki.stm32duino.com/index.php?title=Blue_Pill and use this library (see the examples!) https://github.com/japaric/stm32f103xx-hal There probably will eventually be AVR implementations of https://github.com/japaric/embedded-hal so you could run mostly the same code on an Arduino board.

I know this won't assuage your concerns about officialness, though it's still worth mentioning that Rust does have community-maintained HALs (https://github.com/japaric/embedded-hal ) and tools to generate APIs from official vendor-provided SVDs (https://docs.rs/svd2rust/0.12.0/svd2rust/ ). There's also a few boards out there that do support Rust natively: Hail (https://www.tockos.org/blog/2017/introducing-hail/ ) and Tessel (https://www.tessel.io/ ).