Awesome

UnityHDRPTerrainDetailGrass

A very simple detail shader (hack) for the new Terrain engine 2018.3+

Just download/copy the shader under any folder in your Assets folder. It will replace the current detail shader used by the terrain engine. No idea about performance or optimization. It just receives the detail texture and makes it paintable in hdrp :)

Billboard mode or coloring does not work as of yet. Do not even know if I can make them work :)

Please bear in mind that this is a very basic shader hack. No idea what problems it may cause. Please try/use with caution and definitely back your scene/project up before using this.

Wind

You can control wind using the shader graph itself by modifying the default values in properties window for now.