Maya get all hard edges (note that a mesh may still display smooth if e.g. it had locked normals)

maya_query_mesh_hard_edges.py

from maya import cmds
import maya.api.OpenMaya as om

def get_fn_mesh(mesh):
    sel = om.MSelectionList()
    sel.add(mesh)
    dag = sel.getDagPath(0)
    return om.MFnMesh(dag)

hard_edged_meshes = []
for mesh in cmds.ls(type="mesh", noIntermediate=True, long=True):
    fn_mesh = get_fn_mesh(mesh)
    for i in range(fn_mesh.numEdges):
        if not fn_mesh.isEdgeSmooth(i):
            hard_edged_meshes.append(f"{mesh}.e[{i}]")
            
if hard_edged_meshes:
    cmds.select(hard_edged_meshes, replace=True, noExpand=True)
else:
    cmds.select(clear=True)