PWA – Is App Installed (Windows – Desktop)

I’m hoping someone here has experience with PWAs.

“start_url”: “/”,
“scope”: “/”,
“display”: “standalone”,
“background_color”: “#000”,
“theme_color”: “#00FBFF”,
“orientation”: “portrait-primary”,
 “related_applications”: [{
   “platform”: “webapp”,
   “url”: “https://www.mysite.org/manifest.json”
 }],

I’m trying to check if my webapp has been installed before prompting a user to install it. Below is my JS code and above is my manifest data which is required? 

My console log is an empty array. Any ideas?

https://web.dev/articles/get-installed-related-apps

const relatedApps = navigator.getInstalledRelatedApps();
console.log(relatedApps)