Hi 3D Scan fan,
to create just the depth maps for your active chunk, just use:
#builddepth High quality fo all cameras
Metashape.app.document.chunk.buildDepthMaps(downscale=2, filter_mode=Metashape.FilterMode.MildFiltering, reuse_depth=False, max_neighbors=-1, subdivide_task=True, workitem_size_cameras=20, max_workgroup_size=100)