ARM processors are so cheap these days that I think your idea of “embedded” is a bit stagnant or too focused in one field. I’ve built and shipped a product where it had an ARM processor and ample flash (among a bunch of other components) packaged the size of a key fob and the BOM cost is way less than I used to pay for Arduino or other micro controllers.
Rust is kind of interesting in this space, but a little bleeding edge, will likely look at adopting it later.
Ended up picking an Cortex-M3 and using FreeRTOS. With a C / Lua mix. Not because I particularly prefer them, but it requires the least compromises. Also writing robust embedded C code is pretty well understood with many common patterns. Still, it requires being more diligent and disciplined than many other languages.
You'll always see the crunch at high volume it's just small to medium volume where your options open up. Back when I was in the smartphone business we'd easily see 10M+ volume on a single device and the associated BoM was tuned to a tenth of a penny.
one would hope so, arduino is a retail packing of other chips into a kit.