Does an immutable Linux Distro like this exist?

There is a ton of different linux os so I was wondering if anyone thought of something like this:

The root filesystems is immutable, on top of it would be layered filesystems, but instead of the layers being run on bare metal they would be inside a vm seamlessly. So vm has read only access of the root system(or a shadow root), and everything is layered on top.

Then you would be able to deploy each vm like its own independent desktop (but running the same OS and same DE/window manager, Kind of like KDE activities, but each one in their own VM)

Memory is shared between all VMs and deduped(KSM?) so you don't pay the memory penalty of running the same libraries in ram

Unpacked apps would be installed into a central folder, then linked to and layered on top of for updates to save diskspace of sharing same applications. Of course each would have its own profile data. Of course if it can copy on write the profile data, even better.

Ability to suspend vms to disk to save ram when not used, and restore when coming back. Ability to snapshot vm templates and branch (and push back some changes to the template)

Shareable r/w cache folders (For things like webbrowser cache, docker images, maybe even compiling)

Something tells me I may be looking for a customized version of nixos with a lot of glue and gui that needs to be put together (note I only tried nix for a few minutes in a vm but didn't have time to fully play around with it so I can't say it with full confidence).

I know there is vm based OS like Qubes OS (never tried but heard it is slow due to Xen instead of KVM) and SpectrumOS (there is no ready release yet and I tried to build it but it failed, probably because I wasn't on nixos and didn't have the time to debug it). Though both of those are more aimed at security rather than convenience and optimization. And I'd venture some of the options for optimization would have to give up some security. At least unless a vm is explicitly picked to be private.

But to save myself the time, effort and reinventing wheels or simply being way over my head, anyone seen something like this? Of course I understand that it may be impossible to get 100% of what I want, but if something exists that similar enough with little change that would work too.

To be clear, what I want is a distro that makes it easy to separate workspaces. And that I would be able to come back to those workspaces at any time needed or just discard them. KDE activities would be perfect if not for the fact that apps don't really support them properly, not even KDE's own apps. Suspending activities doesn't really work and they aren't really their own environments. Right now I just use a bunch of my own scripts to glue things together but its a whole mess, especially if pc crashes and I have to restore stuff. And suspending is still a no-go. I was thinking containers would be great, but you can't suspend those with guis. Only thing suspend works on so far is for vms. Hence I am looking for something that can achieve something similar.