> OpenBSD allows making syscalls from static binaries as well.

Do you have a source for this? My Google searches and personal recollections say that OpenBSD does not have a stable syscall ABI in the way that Linux does and the proper/supported way to make syscalls on OpenBSD is through dynamically linked libc; statically linking libc, or invoking the syscall mechanism it uses directly, results in binaries that can be broken on future OpenBSD versions.

Go recently got run through the wringer to remove syscalls (and various Go ports are probably still broken) due to pinsyscalls.