It's interesting that the page actually uses minimax to determine black's play. I kind of assumed it would be a simple lookup table given the small state space of the game. I suppose it makes it easier to add more variants.
const platform = navigator.platform || '';
const userAgent = navigator.userAgent || '';
const isAppleDevice = /iPhone|iPad|MacIntel/.test(platform) ||
/iPhone|iPad|Mac OS/.test(userAgent);
// Set redirect URL and message based on device
const redirectUrl = isAppleDevice
? 'https://www.apple.com/watch'
: 'https://store.google.com/product/pixel_watch_3?hl=en-US';
Edit: per erohead, that change was made after your comment.