Multiple listeners can all listen on TCP port 1433 and this doesnt require the port number to be specified at connection time.
The combination of VIP and port number must be unique which they will be for multiple AGs each with a listener.
Default and named instances can all participate in an AG and they should not be configured to listen on the same port number

See more at this link

https://docs.microsoft.com/en-us/sql/database-engine/availability-groups/windows/listeners-client-connectivity-application-failover