NetBoot was a thing. Apple emphasized heavily from around 1999 to around 2010 or so at which point it still existed but it was continuously de-emphasized until they removed the ability to boot a Mac from the LAN entirely when the T1 or T2 Macs were introduced. It fell out of the "Mac OS X Server" trim level of the OS at about the same rate.
Alongside NetBoot, and probably the more common use case, was NetInstall. NetInstall worked basically how you'd imagine: A Mac OS X DVD was imaged and made available as a boot source. I believe you can also do some other tricks like laying down images with it if you need to, say, set up an identical software installation on 900 MacBooks.
It seems like once Apple finished gutting Mac OS X Server in 10.14,
the option to do a true diskless netboot completely evaporated even from third party solutions.
I've run NetBoot before, however, the easiest way to get it running is to have another Mac, running OS X
Server 10.4/5/6 or -- it can be PPC or Intel, with sufficient disk space/performance to cover the needs of the machines booting from it. Plus, the requisite network connectivity to satisfy your capacity/performance demands. (probably not that big a deal for labs, small setups, and doing installations primarily (vs. just running a bunch of diskless macs.)
The short version of the process is:
- Have a Mac running Mac OS X Server 10.4/5/6
- Enable the NetBoot role
- I don't remember if the OS X server wants to be the DNS/DHCP server but it would probably help, so doing it on an airgapped network or vlan may make this work better.
- Feed the NetBoot image tool a physical CD or a disk image of the OS you want to netInstall or netBoot, or, a prepped/installed image you captured from another machine
- Hold "N" down on the keyboard of the machine you want to boot from the network
In theory, newer versions should run this, but I would guess the practical newness limit is about 10.11 with Server.app or so and I don't know how well that version handles using older images or booting PPCs.
In theory (2) you can do this with open source software or third party mac management tooling from e.g. JAMF, but I don't know how far back compatibility went. Also, almost all of that stuff is
almost certainly now rotting on the vine since NetBoot isn't really a thing Apple wants you to run on your own any more anyway.
EDIT: To add here, you could run OS X Server 10.4/5 on QEMU-PPC or OS X Server 10.4/5/6 (but .5/6 are better) in VMware Player or Workstation on Windows, but I don't have the resources to make that happen handy, especially not in fr-FR, I have a 10.4 client set up in QEMU-PPC in en-US but that, as mentioned, won't actually do the thing.)