Developing software for embedded systems is complex, usually involving a host (desktop PC) to write, test, debug and deploy on a target (embedded). Depending on the type of application and embedded resources (memory, processor type, I/O) the level of support differs widely from system to system:

none = "bare metal"; new systems or systems with minimal memory
SDK, libraries = standard or not
- musl: glibc vs. musl for Linux, vs. uClibc
OS
- Zephyr, FreeRTOS, NuttX, (small MCUs, no virt mem, very limited memory)
- Embedded Linux - see yt for a good overview
  - Yocto / yt intro (not the best...)
- Android

Challenges when developing SW for embedded systems:

limited memory and processor architecture
cross compilation (often different architectures host-target)
specific requirements down to versions of hw, sw, etc.
large software base and space requirements for dev tools
- e.g. Raspberry Pi Pico (HW) with Zephyr 3.6.99 (OS) on Mac OS X Sonoma (Host), aarch64, command line: 13 GB disk space required
  (most is code for other boards). Add an IDE like VSCode and this goes up.

See also associated slides.