User-474980206 posted
this is a fool's errand. There are literally thousands of users agent strings, and almost everyone has given up on using them for this purpose. You can determine some of the most common (apple iPad for example), but laptop vs desktop (no).
what more commonly used now is feature detection, screen size, touch events, etc.
but here is site you can use for reference:
https://developers.whatismybrowser.com/useragents/explore/
there currently have over 21 million agent strings defined.