Best systemd hardening is switching to OpenRC or runit

Do you have any references for doing similar system hardening under either of those?

[dead]

No, switching to Qubes OS is the real hardening.

also true

An unbootable system is indeed harder to exploit!

/s

Why would OpenRC or runit be any less likely to boot?

My response was a joke to a low-effort comment, but in general - systemd is complex because it solves the complex problem of booting up a system, complete with error handling, logging, etc. Many of the alternatives simply ignore part of the problem space, making the simple case simpler, but the complex case impossible.