We had a very interesting discussion about the Hurd. I ran the Hurd before, but now I am going down the rabbit hole of reading device drivers and such. It is very interesting.
I envisage a 'Cloud Hurd' that have minimal hardware demands and a Guix system definition. Running a Guile webserver, for example, could be really, really tiny. ARM support and RISC-V support may come and that will make it even more exciting. Try and trim a Linux kernel to size and you know what I mean. Goblin nano services, anyone? Or an out-of-the-box mail service? It is not about performance, obviously, but about minimalism. I hit this paper online btw - a recent generic writeup: https://www.researchgate.net/publication/373235211_GNU_Hurd_Design_Implementation_and_Future_Prospects_of_the_Microkernel-Based_Operating_System Pj.