A friend of mine and I had a discussion why Browser add workspaces or side-panel like views inside them as I think the usage of multiple windows archives the same effect: separating a bunch of tabs. \
They had the argument that it benefits as many windows get hard to handle when you try to find the right one in the taskbar after minimizing one.
So I had the idea "That's a good point. But why limit it to Browsers and Co and wait for them to implement such stuff (other example is tmux with terminals)".
So I started researching and found a Mastodon post (sorry, but I forgot where it was) that showed a Plasma shell inside a Wayland window.
With some tinkering I came up with this script.
Now to answer your question: it can help to organize a lot of windows, but each Plasma instance takes about 200 MB RAM and also on my computer the main Plasma instance kept crashing after some minutes.
kwin_wayland supports launching Wayland displays inside a Wayland display. This can be used to launch KDE Plasma inside these windowed displays, and that recursive.
Edit: trying to get the image to show on Lemmy