Earlier quoted context omitted.
I've longed for a window manager that can assign different virtual desktops to different screens. Of course, there are compositing, scaling and resolution issues to overcome, but it'd be really neat to have a palette of virtual desktops that could be called up on whichever monitor was most convenient. ...and it'd make screen mirroring during presentations a breeze!
I basically want to have real multi user. I want my dev/project to be an isolated user, also bc of software supply chain security. I want to map it to a (virtual) screen. I want to be able to share the clipboard. I think the closest is running multiple OS X/Linux in VMs
Then, you use a configurable tiling manager to control which windows go where (I am sure you can even go by the user somehow, but maybe you'll need to "decorate" the client run with an env var too).