Launchd is arguably the inspiration for systemd and other modern alternatives. Therefore it's very similar in scope and principle. But many parts of how it works, most notably the configuration file format, are distinctly Apple-isms (or more precisely NeXT-isms) so it probably wouldn't feel "native" to the Linux ecosystem without some substantial retooling of the code.

> many parts of how it works, most notably the configuration file format, are distinctly Apple-isms (or more precisely NeXT-isms)

Basically every type of systemd configuration files are just INI files, which I seem to remember originating in MS-DOS...

I'm not sure about systemd, but launchd uses a rather verbose yet generic xml schema that is used throughout macOS, iOS etc.

It's not even XML, it's a Property List, which can also be represented as JSON or a special binary format: https://en.wikipedia.org/wiki/Property_list

Well, it's also very dependent on running on Darwin.

Apparently it's been ported to some extent to run on FreeBSD: https://wiki.freebsd.org/launchd. I'd expect this job gets harder and harder with each passing year, as the last time Apple released source code for launchd was alongside OS X Mavericks.

Ubuntu actually considered adopting launchd way back in 2006 before systemd existed but: “The option was rejected because the source code was subject to the Apple Public Source License – described as an ‘inescapable licence problem’” [0]

[0]: https://en.wikipedia.org/wiki/Launchd

FreeBSD has been attempting to port launchd since 2005 or so[1]. PC-BSD/TrueOS used to have launchd branch but I think they eventually committed to using OpenRC instead. AFAIK launchd require Mach IPC support in-kernel and require XML parser running in PID 1 so it didn't see much support because of complexity and amount of work it introduces.

[1]: https://wiki.freebsd.org/launchd