It's a mix of Go, Rust, Swift, and C, but I didn't write any virtualization code—it's all built around Apple's Virtualization.framework because that's the only way to use Rosetta in VMs. (The architecture bits are behind a private API in Hypervisor.framework.)
It sounds like it has a ton of great features.
I guess virtualization is its own domain, much like video encoders, cryptography, and systems programming.
Feels like the gateway to those is C and assembly.