Won’t work anyway. You can’t virtualize an Intel macOS on an Apple silicon VM. Unless you were just looking to transfer your data files. If so you can share a directory that is the external TM disk. (Not sure if you can do that with Parallels but the article author’s Viable works fine.)

Not even QEMU can manage it? I imagine it's slow of course, but I'm a little surprised that there's simply no solution. Is this a driver issue or something?

Generally if you say "virtualization" people will assume you mean "use the hardware support to run a VM on the host CPU". For that you must have the same host and guest CPU architecture. Anything else is "emulation", which is perfectly doable regardless of host OS and architecture but often slower than you might like. (QEMU's emulation is not particularly fast, certainly.)

I don't understand why these are worth casually distinguishing, but good to know.

From a user perspective the difference is important, because it's often the difference between "can use this for real work without worrying about exactly what's going on under the hood" and "you probably shouldn't use this unless you know you need to use it and that you can live with the performance aspects". (e.g.: booting a Windows guest under virtualization is a very popular thing to do; booting a Windows guest under emulation is probably going to be a lot of work and not actually achieve the end-goal you were after when you do eventually get it running.) They are also vastly different from a technical perspective.

They are very important distinctions and they are completely different.

Virtualization abstracts the actual underlying hardware, creating a virtual instance. You are executing instructions directly on the host CPU with little or no overhead, so it’s fast.

Emulation mimics one system on a different system by converting the instructions of the mimicked system into instructions the host platform can understand. It is generally a very slow process.

It’s possible and I’ve done it, it’s just unusably slow. If you want to use it solely for terminal usage then it’s bearable.

This supposed experience reminds me of running OS X on Pear PC on Windows.

(1) https://pearpc.sourceforge.net/

QEMU can emulate it.

There has to be a less than pleasant way to hackintosh a vm of the Macbook VM.

A non vm alternative in the meantime is buying and keeping a used iMac to use target disc mode to boot a backup off the hard drive. But who wants to do that.

You may be able to expose it to the client as a SMB network share. But you might also find it easier to back up over a network than to migrate a local backup into the necessary format.

Use qemu and share a drive or put it on network, this should work. Performance of x86 on arm isn't fantastic but more than enough for that.