We are in the middle of converting our Firestore Date object to the new Timestamp Objects
We have done so successfully on the front end by importing firestore
Since you need it inside a cloud function, then you are working with triggers (onCreate, onUpdate...etc) which carries the timestamp via snap parameter. you can use it as below. (it worked with me)
exports.newUserCreated = functions.firestore.document('users/{userId}').onCreate(async (snap, context) => {
firestore.collection(`users/${userID}/lists`).add({
'created_time': snap.updateTime,
'name':'new list name',
}).then(documentReference => {
console.log("list created");
return null;
}).catch(error => {
console.error('Error creating list', error);
process.exit(1);
});
});