How can Hyper-V failover be done without Active Directory
You can build Failover Cluster without AD. It is supported to work with SQL Server role. For VMs Live Migration won't work. Should help: https://techcommunity.microsoft.com/t5/failover-clustering/workgroup-and-multi-domain-clusters-in-windows-server-2016/ba-p/372059
You will need shared storage for the cluster. I am not sure if S2D works in such scenario. You can use alternatives such as StarWind VSAN. https://www.starwindsoftware.com/resource-library/starwind-virtual-san-for-hyper-v-2-node-hyperconverged-scenario-with-windows-server-2016/