Mesh terrain to voxel in Unity, any suggestions?

I am working on 1million+ polygon mesh of terrain visualisation. Can someone give me some pointers how to create a voxel terrain out of a mesh terrain in Unity? Willing to pay for commercial assets as necessary.

When I say some pointers, I did not mean 0xDEADBEEF or 0x8BADFOOD. Thank you.

Edit: removed 2nd link - was not what I thought it was