The 2023 survey, https://blog.rust-lang.org/2024/02/19/2023-Rust-Annual-Survey-2023-results.html, had:

* about 10k respondents
* 14.5% said they target bare metal platforms
* 11.4% said they target embedded targets with an OS (unclear the split between linux/rtos)

So approximately 1500 bare metal users, at least, so I think it's worth surveying embedded topics specifically.