@civodul @bugaevc @janneke This now got me thinking... I found a Hurd post talking about how it adds POSIX compatibility to Mach: https://www.gnu.org/software/hurd/community/weblogs/ArneBab/technical-advantages-of-the-hurd.html
And it says it still provides access to the capability-based permissions underneath, which sounds nice. But it also got me thinking: there's likely to be a lot more software targeting WASI soon, which is natively capability-based. Could it be possible for Hurd to have WASI compatibility too?