was able to pull in the project for the visual studio solution into the main solution for the imgui project. i used that to create build the project. i got a runtime error on line 384:
// Store our identifier
// static_assert(sizeof(ImTextureID) >= sizeof(g_hFontSrvGpuDescHandle.ptr), "Can't pack descriptor handle into TexID, 32-bit not supported yet.");
commented this out to get the basic sample running and it did not crash.
useful to at least investigate/learn more about imgui with DX12