Pipeline to Search 130k Records in Another App and Create if the Record Does Not Yet Exist

What if you have the Pipeline create a Bulk Upsert, and add the one new row to it for the newly created record, and then commit the upsert for that one record.  It will either edit the existing record or add a new one if it does not exists.  If you are just creating one field in table B, then the upsert for an existing record will do nothing, as it already exists.

Since the Login ID in table B is unique, you should be able to use it as a Merge field for the Bulk Upsert.