A website Can easily deduce your phone model based on the browser agent attribute which tells the operating system and the screen resolution with a fair degree of certainty, an app can’t get your phone number, it can get your GPS with your permission. But so can a web page with your permission. There is a standard JavaScript API for it. Contacts are also gated by permissions.

And there is a Contact Picker API for browsers

https://developer.mozilla.org/en-US/docs/Web/API/Contact_Pic...