Exampleのパイプラインを移植するだけでめちゃ時間かかった...
バインドグループ１のレイアウト指定がうまくいっていなかったのが原因で、specializeでパイプラインディスクリプたを作成する際にsetup_morph_and_skinning_defsを使う必要がありました。
この関数のoffsetという引数の意味がよくわかっていません...
また、メッシュをキューに追加する際にMeshPipelineKeyのモーフターゲットの存在チェックをいれたら動きました。

queue_custom_meshes

fn queue_custom_meshes(
    custom_draw_functions: Res<DrawFunctions<Stencil3d>>,
    mut pipelines: ResMut<SpecializedMeshPipelines<OutlinePipeline>>,
    pipeline_cache: Res<PipelineCache>,
    custom_draw_pipeline: Res<OutlinePipeline>,
    render_meshes: Res<RenderAssets<RenderMesh>>,
    render_mesh_instances: Res<RenderMeshInstances>,
    mut custom_render_phases: ResMut<ViewSortedRenderPhases<Stencil3d>>,
    mut views: Query<(&ExtractedView, &RenderVisibleEntities, &Msaa)>,
    has_marker: Query<(), With<DrawStencil>>,
) {
    for (view, visible_entities, msaa) in &mut views {
        let Some(custom_phase) = custom_render_phases.get_mut(&view.retained_view_entity) else {
            continue;
        };
        let draw_custom = custom_draw_functions.read().id::<DrawMesh3dStencil>();

        // Create the key based on the view.
        // In this case we only care about MSAA and HDR
        let view_key = MeshPipelineKey::from_msaa_samples(msaa.samples()) |
            MeshPipelineKey::from_hdr(view.hdr);

        let rangefinder = view.rangefinder3d();
        // Since our phase can work on any 3d mesh we can reuse the default mesh 3d filter
        for (render_entity, visible_entity) in visible_entities.iter::<Mesh3d>() {
            // We only want meshes with the marker component to be queued to our phase.
            if *render_entity == Entity::PLACEHOLDER || has_marker.get(*render_entity).is_err() {
                continue;
            }
            let Some(mesh_instance) = render_mesh_instances.render_mesh_queue_data(*visible_entity)
            else {
                continue;
            };
            let Some(mesh) = render_meshes.get(mesh_instance.mesh_asset_id) else {
                continue;
            };

            // Specialize the key for the current mesh entity
            // For this example we only specialize based on the mesh topology
            // but you could have more complex keys and that's where you'd need to create those keys
            let mut mesh_key = view_key;
            mesh_key |= MeshPipelineKey::from_primitive_topology(mesh.primitive_topology());
            if mesh.morph_targets.is_some(){
                mesh_key |= MeshPipelineKey::MORPH_TARGETS;
            }
            let pipeline_id = pipelines.specialize(
                &pipeline_cache,
                &custom_draw_pipeline,
                mesh_key,
                &mesh.layout,
            );
            let pipeline_id = match pipeline_id {
                Ok(id) => id,
                Err(err) => {
                    error!("{}", err);
                    continue;
                }
            };
            let distance = rangefinder.distance_translation(&mesh_instance.translation);
            // At this point we have all the data we need to create a phase item and add it to our
            // phase
            custom_phase.add(Stencil3d {
                // Sort the data based on the distance to the view
                sort_key: FloatOrd(distance),
                entity: (*render_entity, *visible_entity),
                pipeline: pipeline_id,
                draw_function: draw_custom,
                // Sorted phase items aren't batched
                batch_range: 0..1,
                extra_index: PhaseItemExtraIndex::None,
                indexed: mesh.indexed(),
            });
        }
    }
}

まだサンプルから弄っていないので赤一色で塗りつぶされていますがアウトライン用のパスが追加できました。
パス追加だけでここまで苦労するとは思わなかった。疲れた。

更新順序

LookAt::Cursor

LookAt::Target