Can I access the MsBuildWorkspace from within a MsBuild Task class?

Question

As far as I understand, Roslyn have introduced the concept of Workspaces. One implementation of Workspaces is the MsBuildWorkspace.

My question is, can I from within a

Answer 1

I suspect that this is the purpose of MsBuildWorkspace

No.
The point of MsBuildWorkspace is to parse an MSBuild project or solution into a Roslyn workspace.

MSBuild itself (which is what actually runs your MSBuild task) does not use Roslyn at all (it just invokes the C# compilation task, which is implemented using Roslyn), so there is no existing MsBuildWorkspace that you could fetch.

You could create your own MsBuildWorkspace from the project file.