Only on macOS or Linux do I keep a dock at the bottom. To run a different screensaver on each screen, use Desktop Tools. I tend to just use another 3rd party app to give me back vertical start menus as well. Several third-party tools can do this for you, including DisplayFusion and Desktop. That works well enough really, I don't find I need more desktops inside of the 2 - but they are thankfully pretty separate so I can easily extend into additional workspaces in either if I really need or want to. Tbh after all the work I did to get this feature I have decided not to switch desktops on the 2 separate user sessions, but I do switch desktops a lot on my Linux desktop which RDPs into Windows. Sadly they did not roll that feature into 11 or not yet. I am sure it probably got axed though as Windows 11 went into development and neared release. Not the solution that any of us should want - but as long as they ignore the feature they had already built in a developer insider preview awhile back there isn't much any of us can do about it. I am sure MS would rather users not use something like that, but it may the only way to replicate independent desktops (via hotkeys per 2 different users via RDP sessions).

Tbh I think the only real solution at the moment is something like rdpwrap.

Displayfusion multiple desktops