“Workspaces” have arrived on MirAL trunk (lp:miral).
We won’t be releasing 1.3 with this feature just yet (as we want some experience with this internally first). But if you build from source there’s an example to play with (bin/miral-app).
As always, bug reports and other suggestions are welcome.
Note that the miral-shell doesn’t have transitions and other effects like fully featured desktop environments.