The background_color property is set to a valid CSS color value.
The icons array specifies an icon that is at least 512px by 512px.
The icon exists and is a PNG.
So I uncommented the 512 png in the manifest file.
Then I added a script link to the PWACompat - "the Web App Manifest for all browsers". Much like google fonts it determines your device/browser and makes the relevant changes. https://developer.chrome.com/blog/pwacompat
A browser will show your custom splash screen so long as you meet the following requirements in your web app manifest:
So I uncommented the 512 png in the manifest file.
Then I added a script link to the PWACompat - "the Web App Manifest for all browsers". Much like google fonts it determines your device/browser and makes the relevant changes. https://developer.chrome.com/blog/pwacompat