Exchange hybrid deployment

When configuring our environment for an Exchange hybrid deployment (with Exchange 2019 on-prem), I understand that  we need to make sure certain virtual directories are accessible to Exchange Online.  I'm having difficulty determining exactly which virtual directories to consider.  From what I can tell (not all documentation I've come across is straight forward), it appears to be the Autodiscover and EWS directories...can someone please confirm/correct this?

Thanks for any advice/suggestions!