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