Apart from the Availability Group Listener, is there any other SQL Server listener object that is configured and is in Active Directory?
No. The computer object backing the listener in AD is the only AD object created for AGs and only created when using AD integration.
The Communication endpoint (which listens on port 5022) needs to be granted connect to the SQL service account and this is in SQL.
Certificates can also be used in place of this.
The service account isn't a listener configuration, nor are the endpoints.
What other "listener" configuration should there be?
In terms of configuration for the listener, there are the requirements which much be met in order to create the listener - for example, via T-SQL. Outside of that, there are no other changes/items/configurations needed.