A Storage Spaces Direct (S2D) PoC environment can be deployed either by running it physically or by running it virtually as VMs on top of a hypervisor (Hyper-V or VMware).
Windows Server 2019 Datacenter evaluation can be downloaded freely. It is time-restricted (180-days).
For lab purposes, Microsoft Support can enable S2D in current Windows Server 2019 build.
Microsoft recommends deploying Storage Spaces Direct on hardware validated by the Windows Server Software Defined (WSSD) program. For Windows Server 2019, the first wave of WSSD offers will launch in mid-January 2019.