1. So Ariel OS is based on Embassy - IIUC I2S and CAN has some support upstream. That can be used already, although not using Ariel's usually fully portable APIs.

2. Well, ST has released official Rust drivers for a bunch of their sensors. They're built on embedded-hal(-async), so can directly be used with Ariel OS. There is probably more.

Note: I'm not using the same tooling, but CAN and I2S have worked well for years on STM-32/rust. You just need to interface with STM32's SAI (ditital audio peripheral) and CAN. There are high-quality portable libs for both the legacy "BX" CAN and FD-CAN, which will work on any STM-32 variant. The SAI will have to be HAL-specific, but I have used it on both G4 and H7 variants for PDM mic arrays.