This script will "voxelize" the existing MagicaVoxel model in Unity3D so you can "shatter" it in voxel cubes.

UnityMagicaVoxelize.cs

using System;
using System.Collections.Generic;
using UnityEngine;

public class Voxelizer : MonoBehaviour
{
    public GameObject parent;
    public GameObject voxel;

    private float height, width;
    Collider meshCollider;
    void Start()
    {
        Voxelize();
    }

    public void Voxelize()
    {
        float voxelSize = 0.1f;
        meshCollider = gameObject.GetComponent<MeshCollider>();
        height = (float)Math.Round(meshCollider.bounds.size.y, 2);
        width = (float)Math.Round(meshCollider.bounds.size.x, 2);

        var startPoint = meshCollider.bounds.min + new Vector3(voxelSize / 2, voxelSize / 2, voxelSize / 2);
        var direction = Vector3.forward;

        for (float z = 0; z < width; z += voxelSize)
        {
            for (float x = 0; x < width; x += voxelSize)
            {
                for (float y = 0; y < height; y += voxelSize)
                {
                    var testPoint = startPoint + new Vector3(x, y, z);

                    if (CheckInside(testPoint, meshCollider.bounds.min))
                    {
                        var tmp = Instantiate(voxel, testPoint, Quaternion.identity, parent.transform);
                    }
                }
            }
        }
    }
    public bool CheckInside(Vector3 point, Vector3 startPoint)
    {
        Physics.queriesHitBackfaces = true;

        float rayThreshold = 0.01f;
        float deltaX, deltaY, deltaZ;
        deltaX = (float)Math.Round(point.x - startPoint.x, 2);
        deltaY = (float)Math.Round(point.y - startPoint.y, 2);
        deltaZ = (float)Math.Round(point.z - startPoint.z, 2);

        var ups = Physics.RaycastAll(point, Vector3.up, height - deltaY + rayThreshold);
        var fronts = Physics.RaycastAll(point, Vector3.forward, width - deltaZ + rayThreshold);
        var rights = Physics.RaycastAll(point, Vector3.right, width - deltaX + rayThreshold);


        var downs = Physics.RaycastAll(point, Vector3.down, height - (height - deltaY) + rayThreshold);
        var backs = Physics.RaycastAll(point, Vector3.back, width - (width - deltaZ) + rayThreshold);
        var lefts = Physics.RaycastAll(point, Vector3.left, width - (width - deltaX) + rayThreshold);

        Physics.queriesHitBackfaces = false;

        if (ups.Length > 0 && fronts.Length > 0 && rights.Length > 0 && downs.Length > 0 && backs.Length > 0 && lefts.Length > 0)
            return true;
        return false;
    }
}