How is the MongoDB primary key represented in NoSQL?

MongoDB stores primary keys with the extension _id, but in some environments, a naming standard like resourceId is used, they then use JavaDB mapping to map _id to resourceId. Other Environments just ignore the _id field and create another field named resourceId and give it the UUID data type (which doesn't exist in NoSQL). How would Customers handle these 2 different ways in the NoSQL tool?

Steps:

MongoDB primary keys are stored as _id. This is currently marked as an “objectid” typed field. With respect to UUID related fields, UUIDs are stored in MongoDB as a “binary” type field with a subtype (\x03 and \x04) indicating it is a UUID.

When we reverse engineer this type of field, it will show up as a type of “binary”. In both cases the Customer would have both an _id and a resourceId field created.