The author describes his experience with his transition from macOS to NixOS.
Malware and other applications may install persistent keyboard "event taps" to intercept your keystrokes.
ReiKey can scan, detect, and monitor for such taps!
bhyve is a hypervisor/virtual machine manager developed on FreeBSD.
xhyve is port of bhyve to OS X. It is built on top of Hypervisor.framework in OS X 10.10 Yosemite and higher, runs entirely in userspace, and has no other dependencies.