nostr:npub19ujyvh3q75rrv7mkd8ytqd3ne5lc9357z3z232pj9hwpel7cxs9syrctex Mach and pretty much every other kernel ever written - as kernels don't really care about userspace that much, interfacing the userspace with the kernel is mostly is up to the libc, due to this, most decently written software doesn't care what kernel is in use (with very few exceptions).

There is no "Linux ecosystem" as the kernel, Linux really only has the SYSCALL, /proc and /dev interfaces (nothing that has a feel), such systems are really the GNU system, plus other software that depends on GNU software (or used to in the past).