If an app requires a minimum SDK version of 24, this change means they cannot rely on an available OpenGL ES 3.1 or Vulkan implementation, which is contrary to

If an app requires a minimum SDK version of 24, this change means they cannot rely on an available OpenGL ES 3.1 or Vulkan implementation, which is contrary to the official documentation. So "most apps" will "perform fine" unless they rely on CTS guarantees. If they want to fix the inevitable crashes on third-party ROMs, they will need to perform the same API-level checks that apps needed to perform pre-Nougat. Which is the definition of "fragmentation".