It would be nice for the VM to have access to den setup.

[vic]

For example, boot the VM and use it to edit and nixos-rebuild.

It should be possible to mount the host directory into the VM.

Perhaps using:
https://github.com/Mic92/nixos-shell

According to the docs, it is possible to run linux on Mac, and I believe I once saw a flake for running a macOS with a flake. But maybe, just maybe this is just too much for Den, lets keep default template minimal and provide extra functionality like this in denful.

[vic]

It is already possible you don't need anything extra from what we have today.

I used the following to successfully mount my den configuration and be able to edit from within the VM:

# run the VM with virtfs, the tag is important
nix run .#vm -- -virtfs local,path=$PWD,mount_tag=den,security_model=mapped-xattr

And then inside the VM:

mkdir den
sudo mount -t 9p -o trans=virtio den den
cd den/
vim .
nixos-rebuild switch --flake $PWD