I want to secure and manage 60 (yes, sixty) WANs through SD-WAN on a firewall appliance. What will I need and any recommendations?

I am not new to servers, networking or hardware, but I am new to this side of things.

I have 60 WANs of differing types, but mostly consumer DSL and static IP broadband services. I need to keep all 60 and want to use all 60.

At first I was led to believe that I can use a Layer 2 switch to physically connect each WAN to (like a Cisco Nexus 3064T--but with sufficient ports) and then trunk it to my firewall appliance. The firewall appliance will then allow me to manage all 60 WANs through SD-WAN. This was my initial fairy tale.

However, another engineer told me I need to use a WAN aggregator (not a Cisco 3064T) ahead of the firewall. He mentioned A10 and F5 as two brands to look into, which left my head in a bit of a spin, so I need to ask whether an aggregator really is necessary for this to work period or is it just a way to reduce the count of WANs I expect the firewall to manage?

Thanks in advance to any input you can provide!