If I use Proxmox to run macOS, can I then run Windows under Parallels in the macOS environment?

[Silent3]

Perhaps that's a crazy amount of virtualization to expect to work (not just work well, but work at all).

But would it work?

Further, in the Parallels Windows environment, could I run WSL2? I'll be getting a new i9 12900K CPU, so that should support nested virtualization.

One reason I'm looking into this is, for some reason, the particular i9 CPU in my 2020 iMac, while technically supporting nested virtualization, is terrible at doing so. Running Docker inside a Parallels VM nearly kills the VM, maxing out CPU time and making the VM so unresponsive you can barely type or mouse-click your way out of the situation. An older, less powerful Intel MacBook I have does a much better job at this.

There's nothing newer on Intel coming out of Apple, but I'd still like like a primarily-Mac environment where I can run Windows via VM, and use some Intel-only Windows software, so I'd like to create a more powerful Intel Hackintosh to replace my iMac, still be able to run Windows via Parallels like I have been, but free from crippled nested virtualization.

Using Proxmox sure looks like an easier way to create a Hackintosh than previous methods, but I worry that, unlike the old Hackintosh approach, I'd already be starting out with one layer of virtualization running as soon as I boot up macOS via Proxmox.

Will this be a problem for what I want to do?

 

[LnxBil]

Will this be a problem for what I want to do?

In general: no.

In more detail: it depends.

As you already pointed out, it may lead to extremely slow nested guests and I would not recommend it. For the first guest, MacOS, I recommend to have a pcie passthrough gpu so that you will have near-native speed, but good PCIe performance and a working environment heavily depends on the used hardware. AFAIK, there is no "works" list and the whole subject is also dependend on the used PVE version and kernel, so having a working environment can be hard. As a proof of concept, I also ran a MacOS guest in PVE with Docker without any problem, yet I did not try another guest layer besides Docker - I also don't see the point in that.

Running Docker inside a Parallels VM nearly kills the VM, maxing out CPU time and making the VM

Why don't you run it on your Mac directly? There is the MacOS-internal hypervisor which works great for just Docker.

 

[Silent3]

Why don't you run it on your Mac directly? There is the MacOS-internal hypervisor which works great for just Docker.

I have done this, but it's a bit of a hack, because the software I'm running in the Parallels VM requires access to a company database, which I can only access while running a VPN, and this VPN blocks access to LAN resources. When I run Docker in macOS I actually have to route my Docker application to a WAN IP so the Windows code can find this application on a public URL, which it ordinarily would access on localhost.

As for performance, the problem I was having running Docker inside Parallels on my iMac wasn't that it was running at half speed or quarter speed or even tenth speed. It utterly slagged the VM into uselessness while CPU usage was maxed out. Something pathological was going wrong, not just a simple loss of performance.