VR Headset compatibility

I am , the Founder/CEO of BuCooL INC and I was inquiring about your Unreal Engine 4 opensource capabilities. When using Unreal Engine 4, are the VR headsets, that are listed, the only headsets that are compatible with the software or can other headsets integrate with the software? Also, are the licenses you mentioned in your license agreement, that are allowed, the only licenses allowed or do others apply to the “allowed” list?