It is interesting that they have a day devoted to embedded using MicroBit v2.
The older Rust-Embedded Discovery book [0] also used Microbit but the later edition [1] suggests a STM32F3DISCOVERY. For RISC-V and Extensa fans there is also Ferrous Systems' Embedded Rust on Espressif training material [2] which has a coordinated board [3] that has been "cloned" by Wokwi [4].
My colleguage Andrew wrote the bare-metal part. I believe he picked the micro:bit board because it's readily available around the world. It also has a lot of fun sensors (microphone, rudimentary speaker, compass, ...). I'm sure there are other boards around, but so far people seem very happy with this board in our classroom training.
The only slight problem is the noise when 30 boards are powered on at once :-D They ship with an elaborate demo program which plays sounds and blinks the LEDs when you start it up.
That makes sense. The first was great fun and v2 looks even better. I had written them off due to chip shortages but it looks like availablity is better now.
The older Rust-Embedded Discovery book [0] also used Microbit but the later edition [1] suggests a STM32F3DISCOVERY. For RISC-V and Extensa fans there is also Ferrous Systems' Embedded Rust on Espressif training material [2] which has a coordinated board [3] that has been "cloned" by Wokwi [4].
0. https://docs.rust-embedded.org/discovery/microbit/index.html
1. https://docs.rust-embedded.org/book/index.html
2. https://esp-rs.github.io/espressif-trainings/
3. https://www.amazon.com/dp/B0B4FPV9FW
4. https://wokwi.com/projects/new/rust-esp32-rust-board