This is a tool that allows UnityMeshSimplifier to be used as an NDMF plugin.
Currently this plugin can only be imported by UPM.
https://github.com/lilxyzw/lilNDMFMeshSimplifier.git
This works as a plugin if NDMF is installed.
Just set the quality value. If you simplify a mesh of 10,000 polygons with a quality of 0.5, it will be about 5,000 polygons.
Please refer to the original documentation for other settings.