It's not well known because it's annoying to install ... and it's annoying to install because the stores are huge cash printing machines so that's not going to change.
But of course...
> This is not supported on iOS.
> On iOS 16.4 and later, PWAs can be installed from the Share menu in Safari, Chrome, Edge, Firefox, and Orion.
So you can't have an install prompt, but it's still pretty easy. If people can learn hamburger menus they can learn this.