This is my current Firestore in Firebase.

I need help adding data to the savedSearches map.
I need to use .set() (because a users savedSearches might not exist).
My current attempt looks like this:
database.collection('users').doc(uid).set({savedSearches: data}, {merge: true})
But this doesn't add an object within savedSearches with a unique ID.
When I was using Firebase Realtime Database I was just doing this:
database.ref('users/' + uid + '/savedSearches').push(data)
And that worked perfectly. How can I do that in Firestore?