The report offers a realistic view of the challenges of rating these apps stating "is unique in that it operates in a complex highly connected-interactive socio-technical environment in which frequent changes and modifications can be implemented more quickly and efficiently. Development of software as a medical device is also heavily influenced by new entrants 66 unfamiliar with medical device regulations and terminology developing a broad spectrum of applications."
The framework helps define what is and is not software as a medical device as shown in the first figure below. Based on the potential risk of the software or app, the framework outlines certain steps for review or evaluation - tailored to the risk.
The entire document is long at 46 pages but worth a read for anyone interested in this space. See the second link below.