pfSense

With Wireshark I was able to see that ISC DHCP sets the bootp boot file name and option 60 to HTTPClient. With Kea neither of these things is happening and instead the DHCP option 67 boot file name is being set.

An analogous configuration for Kea that works is like so:

                "boot-file-name": "http://server/file",
                "option-data": [
                    {
                        "name": "vendor-class-identifier",
                        "data": "HTTPClient" 
                    } 
                ]

Rather than as it is now

                "option-data": [
                    {
                        "name": "boot-file-name",
                        "data": "http://server/file" 
                    }
                ]

There's some information here:
https://kea.readthedocs.io/en/kea-2.0.0/arm/dhcp4-srv.html#reserving-next-server-server-hostname-and-boot-file-name

If I understand correctly there should be option 93 like

    {
        "name": "HTTPClient",
        "test": "option[93].hex == 0x0010",
        "option-data": [ { "name": "vendor-class-identifier", "data": 
"HTTPClient" } ],
        "boot-file-name": "http://192.168.200.200/boot.efi" 
      },