I can tell you it runs just fine under KVM...

The reason why at the moment only ESXi is official supported is simply our limited amount of  resources to test every 'virtualization' software available.

As the smg appliance builds up on our appliance framework which is for example also used for the FILR-appliance, guides in transforming/deploying might also come in handy here and can be used at least for the basic deployment until first powerup.

https://www.microfocus.com/documentation/filr/filr-4/pdfdoc/filr-inst/filr-inst.pdf#page=33&zoom=auto,-205,475

There had also been tips in the community about deploying it to XEN/KVM.

https://community.microfocus.com/collaboration/gw/groupwise/smg/i/smg_ideas/smg-appliance-for-kvm-and-or-hyperv-or-just-an-iso?CommentId=09592bfa-1f08-46c1-a202-77160fd650b9#M299

Also works fine under Xen and xenserver/xcp-ng

I'll be testing shortly with Suse Harvester, which uses KVM so not expecting any issues there since kvm already known to work.

You likely won't have any issues, it's just not 'official' as stated since they have limited resources to heavily stress test and sign off on the various hypervisors.