So at boot, one would run "erase-machine-id". Then create a random 30-character hexadecimal number. And then either set "the systemd.machine_id= kernel command line parameter" to it. Or pass it via "the option --machine-id= to systemd".

    % system-control cat machine-id
    start:#!/bin/nosh
    start:true
    stop:#!/bin/nosh
    stop:envdir env
    stop:erase-machine-id
    run:#!/bin/nosh
    run:#Set up and tear down the machine ID
    run:envdir env
    run:setup-machine-id
    restart:#!/bin/sh
    restart:exec false      # ignore script arguments
    %

So "setup-machine-id". Does that generate a value that's unrelated to any preexisting versions, analogs, etc?

I ask because, when I deleted /etc/machine-id and ran "systemd-machine-id-setup", it generated a new machine-id by copying the D-Bus machine ID.