url = 'https://www.hydroshare.org/django_irods/download/efca391eeb4f42d189d4cdf95b3357cd/data/contents/PRISM_ppt_30yr_normal_800mM2_annual_asc1.tif'
The workflow would be to publish that raster data as an Imagery layer. Here is some documentation for doing that using ArcGIS Pro or using ArcMap. Next you can access that imagery layer using the Python API as described in the guide Accessing Imagery Layers
I think direct read of raster data from disk and be able to perform same operations that one could perform on an image service would be a good enhancement for the future.
Retrieving data ...