The Instance, PhysicalDevice and Device are opaque classes that encapsulate the corresponding backends concepts :

Vulkan : VkInstance, VkPhysicalDevice and VkDevice
DirectX : IDXGIFactory4, IDXGIAdapter4 and ID3D12Device

These classes are responsible for the backend initialization and for selecting the best GPU available on the host. If no supported GPU is detected a vireo::Exception is raised when creating the Vireo object.

The only available method is the vireo::PhysicalDevice::getDescription who returns a description of the selected GPU adapter :

const auto& adapterDesc = vireo->getPhysicalDevice()->getDescription();

std::wcout << adapterDesc.name << L" " << std::to_wstring(adapterDesc.dedicatedVideoMemory / 1024 / 1024) << L"Mb" << std::endl;