I'm building a small Shopify store and I want to create some functionality that I have already seen elsewhere. Whenever someone accesses the website on a mobile device, I'd like an overlaid pop up to appear offering to 'Add To Home Screen' on the mobile device - so the web app/site then appears as an icon on the mobile device alongside native apps. When clicked, the icon would open the website home page. I'd like this to work across Android and iOS.
I can provide images for the icon that should go onto the mobile devices.