As a bonus option, potentially for interop reasons, it is possible to create a bonafide DisplayStyle for linework. Still, it is more involved in using the C# script component and the Speckle Objects library.
If you add the SpeckleCore2.dll from Rhino plugins, netstandard.dll assembly, and the Speckle Objects assembly (all these are installed as a consequence of the plugin installation - see our docs)
You can create any of the Speckle Objects this way over and above those backed into the Speckle BIM ribbon.
In this example, I am still passing the output to the displayStyle property, which is probably an unnecessary complication but demonstrates expanding Speckle code further in your Grasshopper workflows.