You will need to add your shader to Source/Shaders/Materials (For example, this is the PolylineGlowMaterial shader)
Then you can add a new type to Material.js (This is where the PolylineGlow type is added)
Then you need to create a new MaterialProperty (see the PolylineGlowMaterialProperty)
Lastly, you need to make changes in GeoJsonDataSource to use your new property. So change options.strokeMaterialProperty to use at material for all lines (including polygon outlines), or make a change in createLineString to make certain polylines use the pulse material.
And I think that’s it. Let me know if you have any trouble and I’ll try to help
If you do create this new Polyline material, consider contributing it back to us =)
It sounds like something other people would be interested in using too.