I haven't seen any plans for teensy. There's some work being done in the AVR area github.com/embassy-rs/embassy/pull/2273 This is the only teensy crate I'm aware of atm: github.com/mciantyre/teensy4-rs
I’m looking forward to more embedded Rust content. I did a tiny bit of experimentation with it last year until PC tools and web servers became a more pressing need. I want to get back into embedded.
I don't have a good answer for this. I'm just reading a lot and trying some things. Getting Rust onto a board and running isn't too bad, there's quite a few places to get that (microbit, embassy, etc), but building real actionable projects is definitely a whole different step. I started with the microbit: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-b7zWIKZp4ls.html and then I did some pico w work: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-vwFWBP0IuRU.html and now I have a little set of electronics and whatnot that I'm working through.
The esp32 HALs are maintained by the esp-rs org on github and can be used with embassy (github.com/esp-rs). There's a couple of additional links to esp32 resources in the embassy readme on github as well. I didn't mention this in the video because the video is mostly about the crates *from the embassy repo* that are now published, but esp32 is supported!
embassy reserved the names for the crate names they are using while development was progressing on GitHub so that they could publish when the crates were ready (being able to use Rust's stable release was one concern, for example). The core "embassy" crate is one of those. I don't know what the plans are for the embassy crate itself, but that's what's happening there.