The only option for creating a new conda environment in ArcGIS Pro is "Clone Default". There is no way to create an environment for a specific task without copying all the packages from an existing environment.
Could you provide some context to what you'd like to see in terms of making a new environment? The Python environment creation is geared around making Pro-compatible environments as most users later expect to use them with Pro. Are you interested in making environments that aren't connected to Pro and contain an arbitrary set of packages? If so, you may also be interested in Anaconda Navigator.
