HTML5 Webapp as regular icon or app on iPhone and Android.
No need for PhoneGap or a launcher on the iPhone.
Per Apple:
<link rel="apple-touch-icon" href="/custom_icon.png"/>
Documentation and more fun options you can add to your web app:https://developer.apple.com/library/content/documentation/AppleApplications/Reference/SafariWebContent/ConfiguringWebApplications/ConfiguringWebApplications.html
PhoneGap is an open source wrapper for local web apps that runs on several mobile platforms. There is no reason you could not use it with hosted web pages as well.
Apple would probably reject something they deemed equivalent to a web bookmark.
I think you have to develop a "launcher" app that will just invoke the browser and send the user to your web application.