ASEV3 Egress Networking

Question

Hello everyone, My customer has questions around opening up Egress traffic for specific apps only to have outbound access to services outside the ASE Vnet. They are using Azure firewall and opening up the ASEv3 subnet CIDR range will actually open up access for all apps hosted within the app service environment to external services. We are good with the ingress though for an ILB ASEv3 behind AppGW which is configured with listeners on a per app basis, so the ones which are not to be exposed to the internet are not configured in the AppGW listener. The problem is with egress traffic and I can't seem to find ways to configure Azure Firewall using the FQDN either, only IP and IP Group is available. Any insights is appreciated.