How to point Azure Hybrid Connection to Availability Group Listener ? Or redirect to secondary replica?
You should be able to connect to the AG listener  from Azure to On-premises or vice versa--though it's not as straight forward as you might think. Here's one of the best article's I've ready today on how to do it.

https://www.concurrency.com/blog/w/creating-a-listener-for-a-multi-subnet-hybrid-or-a

When the AG primary node is on-premises (or in Azure), you should be able to connect to the listener. So you're relying on Azure DNS to do it's job properly and resolve your SQL Azure node correctly. Haven't tried it myself--sounds awesome!