I don’t know if this is a bug or a request but I’m handling it as a bug. (edit: moved it to feature requests)
When you open an apps URL on iPhone on Google Chrome you get the prompt to add the app to your home screen. This can’t be done in Google Chrome. You must open the URL I safari to be able to add it to your home screen.
A fix for this: let the site check if your on Safari and if not, prompt the user to open in safari.