Reading GH_Archive Types like Meshes, Breps

So this might be a very stupid question but I am down the rabbit hole with Rhino.Compute and I am trying to read a .ghx Archive so that I can use the Resthopper functionality in Rhino Compute. I have managed to cast basic parameters like points, doubles using the:

GH_IReader reader;
reader.GetPoint3D(name)

I am now trying to cast a mesh but there is no GetMesh() method within the IReader class. Am I missing it from somewhere? At any rate I have something like this in the .ghx

<item name="ON_Data" type_name="gh_bytearray" type_code="20">
<stream length="3515">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</stream>
</item>
<item name="RefID" type_name="gh_guid" type_code="9">00000000-0000-0000-0000-000000000000</item>
</items>

I am able to get the stream as which I thought to cast it to a mesh using:

string base64Data = System.Convert.ToBase64String(reader.GetByteArray(name));
var commonObject = Rhino.Runtime.CommonObject.FromBase64String(0, 0, base64Data);
return commonObject as Mesh;

which is not working.

The obvious way of doing it seemed to be the

GH_Archive archive;
archive.ExtractObject(<?>, <?>);

however, I have no idea what to put as argument, as each item is not “named” within the archive. Also, when I used this functionality in the past within Grasshopper I had access to RhinoCommon.dll which I don’t have at the moment, because I am using rhino3dmio.dll and would throw a conflict. Obviously I am trying here meshes but this question would be the same for other types like breps.