Yes, so what will the target-audience learn over the virtual experience? Other than that they can't run this at home because of the cost?
I think you initially misunderstood this to be a consumer-oriented project instead of a classroom-oriented project, but doubled down when you were corrected.
Glib reply: why not?
Serious reply: VirtualBox is available for Windows, macOS & Linux alike, and is free. Surely that's acceptable?
Serious response: I'm of the opinion that you don't learn much about Linux by using it in VirtualBox.
The really cool thing, though, about multiple Raspberry Pis is that the systems really are running in parallel, rather than faking it with multitasking. That's definitely worth something in an educational context.
Still, I think there's value in having this cool looking machine to fiddle with over the computer they're used to messing with all the time. I think it likely to engage more.
Technically, a single PC with multi-process program is often enough. I've used this approach when I worked on some cloud game server, worked good, I just needed to make sure service discovery was OK finding multiple server instances on same IP but different ports.
As opposed to running it by yourself on your own computer in a bunch of virtual machines?
Imho, multitasking is a much cooler feat than parallelism by mere duplication of the CPU. It requires much more engineering effort, e.g. in areas of memory coherence and such. Also, a modern desktop CPU will be an order of magnitude faster than the RPi, so you'll need a lot of them to match performance.
> Other than that they can't run this at home because of the cost?
Do you really think that, as an example, a middle school student is going to be able to go home and install virtual box on their home computer? If they even have one?
As a kid, I would do something in a virtual environment (although at that time, that meant "programming the ZX Spectrum") and the others would say "does not!" or "prove it" and then any evidence they couldn't touch was not real, it was just something I made the computer do.
On completion of my CS degree, some former friends of mine would read something at an appropriately undergrad level that they thought was interesting and tell me about it. When asked "Can you not do that?" the response would typically be "No. And neither can you."
There's something quite satisfying about building something that you can throw at the head of another person.