NPS or CX Measures for Nonprofit Organizations

I am working with a colleague on a research project for a healthcare foundation.  It’s a 501(c)(3) and I am looking for any benchmarks that might be out there.  I ran some searches on Google and here at Qualtrics.  I could not find anything specific.  I am firm believer that the strategy and methods are similar if not the same for developing a Net Promoter System or Customer Experience Management System.  I’d just love to learn about any benchmarks for NPOs, and specifically in healthcare.  Looking forward to any information you may have to share, or help create a solution!  Best, Mary