The model looks entirely smoothed out on all edges, the workaround is to export the model from blender to FBX and then upload to sketchfab although that causes animation issues in my specific case.
In blender you can see the blue edges that should get exported. https://i.imgur.com/VxyEhmU.png
And if exporting as FBX and then uploading I get the expected result on the edge sharpness as seen here. <can’t post two links>
A fix for this lack of sharpness in the export to sketchfab plugin is much needed, especially due to how an increasing amount of addons use this sharpness feature.