Derive from CustomNodeManager2 (I named it DataAccessNodeManager) and add the following method to it:

private NodeId AddDataType<T>() where T : struct, Enum
{
    var enumFields = Enum
        .GetNames<T>()
        .Zip(Enum.GetValues<T>())
        .Select(item =>
        {
            return new EnumField
            {
                Name = item.First,
                Value = Convert.ToInt32(item.Second)
            };
        })
        .ToArray();

    var enumDefinition = new EnumDefinition { Fields = enumFields };
    var nodeId = new NodeId(++_nodeId, NamespaceIndex);

    var enumType = new DataTypeState()
    {
        NodeId = nodeId,
        BrowseName = typeof(T).Name,
        DisplayName = typeof(T).Name,
        SuperTypeId = DataTypeIds.Enumeration,
        DataTypeDefinition = new ExtensionObject(enumDefinition)
    };
    
    AddPredefinedNode(SystemContext, enumType);

    return nodeId;
}

Then, in your derived class, use it as follows:

class DataAccessNodeManager : CustomNodeManager2
{
    public DataAccessNodeManager(IServerInternal server)
        : base(server, ...)
    {
        //
    }

    public override void CreateAddressSpace(IDictionary<NodeId, IList<IReference>> externalReferences)
    {
        lock (Lock)
        {
            var myNodeId = AddDataType<HlbCompressor>();

            // ... add other nodes and use myNodeId for the `DataType` property 
        } 
    }
}

The often used UaExpert client software then shows the enum name next to its value: