Comment by thaumaturgy

You can get pretty close to this with VirtualBox, which is one of two reasons I'm still using it.

I have multiple VMs running on my laptop. I can attach an external display and resize the VM windows. When detaching the display, the windows all resize back down automatically. With shared clipboard and a few other niceties, each VM feels pretty close to a native experience.

I have single-application VMs (e.g., the one that hosts my daily-driver browser environment that I'm typing into right now); those run a lightly customized openbox environment and the application is full-screened inside the VM. Those really feel like a Qubes-like experience, like a native application but inside a VM.

I also have purpose-specific VMs. For example, anytime I get started on a new contract, I spin up a new VM for it. All credentials, dev tooling, files, etc. for that project are contained inside that VM. I typically set it up so that there are multiple virtual desktops on my host environment, but a single desktop inside the VM; alt-tab switches tasks inside the VM but not the host environment. So, it's easy to switch "into" the project VM, work there for a while as naturally as I would if everything were native, and then switch out again as needed.

I really really want to swap all of the VirtualBox bits out with QEMU or KVM, but those aren't quite as polished just yet -- despite VirtualBox's numerous and sometimes work-stopping bugs, and the ever-looming threat of Oracle's litigation team.