How to pass geo from vtk to netgen & pass mesh from netgen to vtk directly without needing to exporting/read file?

Support
1

Following code can export meshing result as vtu file

from netgen import occ, meshing
from ngsolve.utils import *
from vtkmodules.vtkIOXML import vtkXMLUnstructuredGridReader

from ngsolve.comp import *
from ngsolve.solve import *

# from netgen.csg import unit_cube
# mesh = unit_cube.GenerateMesh (maxh = 0.2)

# load geo
geo = occ.OCCGeometry('../resource/frame.step')

# generate mesh from geo
mesh = geo.GenerateMesh(maxh = 1000, perfstepsend = meshing.MeshingStep.MESHSURFACE)
# convert to ngsolve mesh
mesh = Mesh(mesh)

# export mesh as mesh.vtu
v = FESpace(type = "hdivho", mesh = mesh, order = 1, dirichlet = [1, 2, 3])
u = GridFunction (space = v)
vtk = VTKOutput(ma = mesh,
                coefs = [u],
                names = ["density", "velocity"],
                filename = "mesh",
                subdivision = 3)
vtk.Do()

# read exported file: mesh.vtu
reader = vtkXMLUnstructuredGridReader()
reader.SetFileName("result.vtu")
reader.Update()

Geo can be exported from vtk pipeline also,my questions are:

1, How to pass geo from vtk to netgen directly,not need to export files?
2, How to read mesh from netgen directly,not need to export/read files?
2

For reference: Duplicate stackoverflow post can be found here.