Disc Golf Metrix is a web application designed to be responsive and work on all devices using most common web browsers. That's why we do not have native applications for different mobile phones, but focus on developing the best mobile experience possible with single solution.
Disc Golf Metrix also support entering scores during the round without network connection. And will save the results once the connection is established again.
In order to use Metrix like a native a, one can easily create a home page shortcut. On most mobile browsers there is an "Add to Home screen" action in the browser settings. Here's an example from an Android phone, when using Chrome.
More detailed instructions for different phones can be from here: https://www.howtogeek.com/196087/how-to-add-websites-to-the-home-screen-on-any-smartphone-or-tablet/