Don’t understand the question … please make clear.
is it always create horizontal surfaces or pergolas?
If you see the input options you’ll notice that there is an option to set an angle for the shaders. You can use it. It works nicely.
Can we create a third option?
There is indeed a third option. Again notice that you can provide a surface input. It is intended to calculate what part of this surface is needed to provide shade for the period defined. Also works nicely. The down side of this option is that it doesn’t guarantee to provide the shade for your window fully if the surface is too short or not wide enough.
Hope this helps.
And welcome to the discourse.