Example using Alembic python api to get the full inclusive matrix for objects in the .abc file.

alembic_get_inclusive_matrix.py

import alembic.Abc
from alembic.AbcGeom import IXform

kWrapExisting = alembic.Abc.WrapExistingFlag.kWrapExisting


def get_matrix(obj):
    if not IXform.matches(obj.getHeader()):
        raise TypeError("Object is not an xform: {0}".format(obj))

    x = IXform(obj, kWrapExisting)
    xs = x.getSchema().getValue()
    return xs.getMatrix()


def get_inclusive_matrix(obj):
    """Return inclusive matrix of Alembic Object"""
    matrix = get_matrix(obj)
    parent = obj.getParent()

    while parent:
        try:
            parent_matrix = get_matrix(parent)
        except TypeError:
            # Parent is not an xform
            break

        matrix *= parent_matrix
        parent = parent.getParent()

    return matrix
    

def get_alembic_transforms(filename):
    """Return transform matrices from the Alembic hierarchy

    Arguments:
        filename (str): Full path to Alembic archive to read.

    Returns:
        dict: Mapping of node full path with its world-space matrix.

    """

    # Normalize alembic path
    path = os.path.normpath(filename)
    path = path.replace("\\", "/")
    path = str(path)  # path must be string

    archive = alembic.Abc.IArchive(path)
    root = archive.getTop()

    node_matrices = {}
    iterator = list(root.children)
    for obj in iterator:

        # Include children children
        iterator.extend(obj.children)

        node_path = obj.getFullName()
        
        # Check if is transform
        if not IXform.matches(obj.getHeader()):
            continue
        
        matrix = get_inclusive_matrix(obj)

        node_matrices[node_path] = matrix

    return node_matrices
    
path_matrices = get_alembic_transforms(path)
for node_path, matrix in path_matrices.items():
    print(node_path)
    print("\t{0}".format(matrix))
    
    
# Example output:
# /character_GRP/eye_L_GES
#     M44d((1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 1, 0), (0, 0, 0, 1))
# /character_GRP/mouth_GRP/back_mouth_GES
#     M44d((1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 1, 0), (0, 0, 0, 1))
# /character_GRP/tongue_GES
#     M44d((1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 1, 0), (0, 0, 0, 1))
# /character_GRP/stand_GES
#     M44d((1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 1, 0), (0, 0, 0, 1))
# /character_GRP
#     M44d((1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 1, 0), (0, 0, 0, 1))
# /character_GRP/eye_R_GES
#     M44d((1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 1, 0), (0, 0, 0, 1))
# /character_GRP/body_GES
#     M44d((1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 1, 0), (0, 0, 0, 1))
# /character_GRP/mouth_GRP
#     M44d((1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 1, 0), (0, 0, 0, 1))
# /character_GRP/mouth_GRP/teeth_GES
#     M44d((1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 1, 0), (0, 0, 0, 1))