Can anyone confirm if Sophos XG Home will work on a Mac Mini, I keep getting the msg "Failed getting ISO disk" when trying to install? Currently have UTM v9 installed without issue.

I don't think so for two reasons. First a specific and non-standard EFI implementation. I don't know if SFOS even supports install in EFI mode. The second reason is only one onboard ethernet interface.

I can also add that SFOS do not support USB based Ethernet cards as far as I was able to check which is a little bit disappointing because Linux kernel do not have problems with most of them.

I suggest two workarounds:

Use VirtualBox and create virtual appliance or

Ditch OS X, setup up a Linux distro such as Ubuntu or Fedora and use KVM to host prebuilt virtual appliance. I can attach KVM XML definition of VM if needed.

Could you attach your KVM XML definition of VM? I am going to get an Ubuntu system up and would appreciate any help getting XG working on it.
Thanks,
Chappcc

Download KVM version of SFOS firmwre and try the following definition (put it in sfos.xml):

<domain type='kvm'>
    <!-- General Settings -->
    <name>sfos</name>
    <uuid>place_your_uuid_here</uuid>
    <title>Sophos XG OS</title>
    <description>Test firewall</description>
    <!-- Operating System -->
    <os>
        <type>hvm</type>
        <boot dev='hd'/>
        <bootmenu enable='yes' timeout='3000'/>
    </os>
    <!-- CPU -->
    <vcpu>2</vcpu>
    <!-- Memory -->
    <memory unit='GiB'>4</memory>
    <currentMemory unit='GiB'>4</currentMemory>
    <!-- Events -->
    <on_poweroff>destroy</on_poweroff>
    <on_reboot>restart</on_reboot>
    <on_crash>restart</on_crash>
    <on_lockfailure>poweroff</on_lockfailure>
    <features>
        <acpi/>
    </features>
    <clock offset='utc'/>
    <devices>
        <!-- Which emulator to use -->
        <emulator>/usr/bin/kvm</emulator>
        <!-- Disk devices -->
        <!-- Main disk -->
        <disk type='file' device='disk'>
            <driver name='qemu' type='qcow2'/>
            <source file='/srv/vms/sfos/PRIMARY-DISK.qcow2'/>
            <target dev='vda' bus='virtio'/>
        </disk>
        <!-- Auxiliary disk -->
        <disk type='file' device='disk'>
            <driver name='qemu' type='qcow2'/>
            <source file='/srv/vms/sfos/AUXILIARY-DISK.qcow2'/>
            <target dev='vdb' bus='virtio'/>
        </disk>
        <!-- Network devices - two network cards attached to different bridges. -->
        <interface type='bridge'>
            <source bridge='virbr1'/>
        </interface>
        <interface type='bridge'>
            <source bridge='virbr0'/>
        </interface>
        <!-- Input devices -->
        <input type='tablet' bus='usb'/>
        <input type='mouse' bus='ps2'/>
        <!-- Output (Graphics) device -->
        <graphics type='vnc' port='5901' listen='0.0.0.0' passwd='sophos' />
    </devices>
</domain>

virsh create sfos.xml will do the trick. As you can see it comes with two disks by default.

Drop a note if you need help with Ubuntu networking.

Download KVM version of SFOS firmwre and try the following definition (put it in sfos.xml):

<domain type='kvm'>
    <!-- General Settings -->
    <name>sfos</name>
    <uuid>place_your_uuid_here</uuid>
    <title>Sophos XG OS</title>
    <description>Test firewall</description>
    <!-- Operating System -->
    <os>
        <type>hvm</type>
        <boot dev='hd'/>
        <bootmenu enable='yes' timeout='3000'/>
    </os>
    <!-- CPU -->
    <vcpu>2</vcpu>
    <!-- Memory -->
    <memory unit='GiB'>4</memory>
    <currentMemory unit='GiB'>4</currentMemory>
    <!-- Events -->
    <on_poweroff>destroy</on_poweroff>
    <on_reboot>restart</on_reboot>
    <on_crash>restart</on_crash>
    <on_lockfailure>poweroff</on_lockfailure>
    <features>
        <acpi/>
    </features>
    <clock offset='utc'/>
    <devices>
        <!-- Which emulator to use -->
        <emulator>/usr/bin/kvm</emulator>
        <!-- Disk devices -->
        <!-- Main disk -->
        <disk type='file' device='disk'>
            <driver name='qemu' type='qcow2'/>
            <source file='/srv/vms/sfos/PRIMARY-DISK.qcow2'/>
            <target dev='vda' bus='virtio'/>
        </disk>
        <!-- Auxiliary disk -->
        <disk type='file' device='disk'>
            <driver name='qemu' type='qcow2'/>
            <source file='/srv/vms/sfos/AUXILIARY-DISK.qcow2'/>
            <target dev='vdb' bus='virtio'/>
        </disk>
        <!-- Network devices - two network cards attached to different bridges. -->
        <interface type='bridge'>
            <source bridge='virbr1'/>
        </interface>
        <interface type='bridge'>
            <source bridge='virbr0'/>
        </interface>
        <!-- Input devices -->
        <input type='tablet' bus='usb'/>
        <input type='mouse' bus='ps2'/>
        <!-- Output (Graphics) device -->
        <graphics type='vnc' port='5901' listen='0.0.0.0' passwd='sophos' />
    </devices>
</domain>

virsh create sfos.xml will do the trick. As you can see it comes with two disks by default.

Drop a note if you need help with Ubuntu networking.