I've found that the PowerMac era of hardware is emulated at a 'technically works but pretty janky' level. Particularly when emulating OS 9 rather than OS X.

For me QEMU works very well for running OS9 on a contemporary mac. I don’t use it heavily so I can’t promise that it’s glitch free, but I’d recommend trying it before seeking out old hardware, unless you particularly want to run old hardware.

This was my first attempt, but

a) SheepShaver doesn't quite emulate the experience, e.g. the mouse movements appear to have a slight lag, some icons don't draw, etc. and

b) I didn't manage to set up network there and found no guide of how to get files to that VM in any other way.

So overall I decided to just try a real machine and got it for around ~$50 in the local fleamarket. Tried Ebay first, found a great candidate (Powerbook G4 1Ghz/Ti, last model capable of booting Mac OS 9), but there was quite a few bidders and the price went up to ~$450, so I passed.

It would need to be more than just a virtual machine, it would need to be an emulator. Different architecture, different endianness, etc.

I'd say it's a virtual machine employing emulation, just different vernacular.