I am the creator of Redox, and I am glad to have this rundown. Yes, the design of the Redox kernel is such that the kernel can load any set of drivers from the initramfs, including being completely diskless.

In order to make this easy, ELF loading is part of the kernel. Otherwise, the ELF loader would have to be loaded somehow. How does QNX solve this issue? I could see there being a simpler executable format, or maybe the loader could do what the kernel does and modify its own paging tables.

With regards to the book, it was outlined by a contributor who is no longer part of the project, so it is likely to be restructured when there is time, and the sections may change.

There are drivers for what are considered to be critical features for any userspace inside the kernel. This mainly means the interrupt controller, but has included a serial console for kernel debugging. This will be an optional component in the future.