@boot could be used to launch a userland app starter (as per my comments in a related thread).

Or user could configure their systems so that apps are run immediately that the kernel starts (or shortly afterwards) by using it.

I can't think of any right now, but it could make the empeg 'pre-init' program less of a issue, in that if you can launch apps you want at boot up, then why bother with any other mechanism just yet?

Of course, we have to be able to make kernel space launched apps run without issues like any normal userland app would.

I am not sure if starting every app from the kernel is a good idea, starting most apps from userspace would help protect to some extent the system from badly behaved apps I suspect.

But right now, being able to launch anything reliably on demand is a real holy grail and I don't much care how we get there as long as its simple to deploy and configure.