Based on a cut-down browser, Help Viewer, Apple Help in Mac OS X has had its ups and downs, and several internal revisions, the latest of which is the Tips app in Sequoia.
NSHelpManager
Help has been in steady decline since macOS 10.13. More recently, when you open a Help book on an Intel Mac it may get buried, but it doesn’t on M-series Macs. Why?
All about helpd and HelpViewer, how they index and maintain Help books. And what has gone wrong recently, including an odd difference between Intel and Apple silicon Macs.
Key improvements in naming of Help books, use of WebCore to render them, and greatly improved performance.
macOS 10.13.4 brought a major overhaul to the Help system, which greatly improves performance and usability. Here are some of its secrets.
Trying to decide whether a selected item is an app bundle turns out to be simple, if you cheat.
The Eclectic Light Company 