Like the article points out, the software stacks people use for embedded devices are the same as people use non-embedded use; Rust, Go, NodeJS, and sure still C++. The only real difference with embedded devices is non-OS components like the bootloader (u-boot, EDK2) and customizing the device tree. (And of course firmware flashing). Fundamentally those are all just packages that I can describe in Nix. I don't need a separate tool just because the board is small.
IMO the embedded space, especially in the US, is already pretty Niche. Most companies either just ship the vendors BSP example (Ubuntu/Debian/Yocto) and pay very little attention to the detail or re-useablity. Once you vendor declares the BSP EOL you are stuck unless you re-implement it yourself.
Using Nix (or Guix) has the massive advantage of a large and active community that isn't fractured like the Yoctoo/Buildroot community. (By fractured I mean there may by many, many people using those tools at $DAYJOB but due to vendor BSP customization they likely share much less with the upstream community maintained sources).