Here are the ones used by lodestar's beacon-node and state-transition (including those that are used in upcoming glamsterdam). List might be non-exhaustive:

• ListCompositeTreeViewDU.sliceFrom()
• ListCompositeTreeViewDU.getAll()

const TV = ssz.TreeView(Validators);
const view = try TV.init(...);
var out: TV.SszType.Type = undefined;
try TV.SszType.tree.toValue(view.data.root, view.pool, &out);

• ListCompositeTreeViewDU.sliceTo()
• ListBasicTreeViewDU.push()
• ListBasicTreeViewDU.sliceTo()
• ContainerTreeViewDUType.serialize()
• ContainerTreeViewDUType.deserialize()
• ContainerTreeViewDUType.toValue()

const TV = ssz.TreeView(BeaconState);
const view = try TV.init(...);
var out: TV.SszType.Type = undefined;
try TV.SszType.tree.toValue(view.data.root, view.pool, &out);

• ContainerTreeViewDUType.type.tree_serializedSize()
• ContainerTreeViewDUType.defaultViewDU()
• TreeViewDU.clone()
• TreeViewDU.serializeToBytes()
• ListCompositeTreeViewDU.push()
• BitArrayTreeViewDU.toBoolArray()

const TV = ssz.TreeView(AggregationBits);
const view = try TV.init(...);
var out: TV.SszType.Type = undefined;
try TV.SszType.tree.toValue(view.data.root, view.pool, &out);

Prerequisite of #20