I was listening music on YouTube Music, and noticed a new entry on Google Chrome's menu offering to Install YouTube Music....
This option does not appear on non-YouTube Music pages, or in an incognito session.
The entry isn't available in Firefox, either:
Does the website declare the availability of that menu entry somehow? Can my own website add any such entry to Google Chrome's menu? Are there any other such entries that can be shown in Google Chrome?
The screenshots are all on macOS, but this entry shows up in Google Chrome for Windows, too (haven't tried incognito or other browsers in Windows).