Extracts mesh data to be used for mesh.from_pydata()

mesh_copy.py

import bpy
from mathutils import Vector

# prereq: go into your object's edit mode
context = bpy.context

mesh = context.edit_object.data

verts = [v.co for v in mesh.vertices]
edges = [[v for v in e.vertices] for e in mesh.edges]
faces = [[v for v in p.vertices] for p in mesh.polygons]

print(verts)
print(edges)
print(faces)
    
bpy.ops.object.editmode_toggle() # back to object mode

mesh = bpy.data.meshes.new("myBeautifulMesh")  # add the new mesh
obj = bpy.data.objects.new(mesh.name, mesh)
col = bpy.data.collections["Collection"]
col.objects.link(obj)
context.view_layer.objects.active = obj

mesh.from_pydata(verts, edges, faces)