Very relevant to this discussion. I read about postmaketOS earlier today and I think it sounds great. It's a good example of why Halium is not the answer to our prayers. The developer of postmaketOS shares several ideas with where I plan to take my OS. I find it very positive that he has chosen to base it on Alpine Linux which I am a huge fan of (grsecurity, musl libc, no systemd). I plan to do things the other way around though: mainline Linux is my immediate goal rather than my long term goal. I'll share more details on my OS later.

P.S. Despite my views on binary blobs, I haven't ruled out using libhybris for certain devices that run on mainline Linux but it is not a priority.