Basically I'm trying to write a better Linux than Linux and a better QNX than QNX, at least for certain use cases that is. At least initially, my primary focus is on workstation/enthusiast desktops and higher-end embedded systems (some types of servers, especially ones where high security is important, are also a focus as well but maybe not quite as much for now). Pure consumer desktops aren't really much of a priority; the goal is to make something that's approachable but definitely not dumbed down. Almost every day I see people complaining about mainstream OSes and I think there's an opportunity for an OS that's cleaner and more integrated than Linux and has various advanced features not found in Linux, but still tries to maintain a high degree of compatibility with it. I'm not really trying to clone QNX or Linux 1:1, but I am trying to maintain similar enough semantics to allow easy implementation of compatibility layers for both systems.
At the moment I have a working microkernel and an incomplete process server with a partially-implemented VFS but no support for running regular user processes. Currently I am working on some of the first special filesystems built into the process server (specifically an early log/console device at the moment).
The kernel is a hard fork of seL4 (the biggest addition at the moment is a preliminary implementation of QNX-style arbitrary-length arbitrary-address message copying); I've forked it because seL4 is focused on lower-end static embedded systems, and full verification of just the kernel isn't really particularly useful for a dynamic OS when all of the servers are unverified. The process server is written in Rust, and it's likely most of the other low-level servers will be as well, although I'm not really writing a "Rust OS" as such. Many of the basic utilities will most likely be BSD-derived, and some of the higher-level desktop-related stuff may be written in various other languages (haven't completely decided there).