Can writing about accomplished worldly individuals be considered Guru service, and how does it compare to writing about saints?

Yes, Chapter 0 explains that writing biographies of great worldly figures like politicians, jurists, or writers is a form of Guru service and public service. However, this service is worldly in nature, and its fruits are not eternal, being limited by time and space. It is often rooted in self-interest and therefore does not yield spiritual benefits. In comparison, writing the biographies of saints is also a form of Guru service that does produce spiritual fruits. Yet, the text in Chapter 0 cautions that both of these approaches are considered one-sided or partial, and attaining the ultimate spiritual goal solely through these means is difficult, if not impossible.