HTML5 based apps are effectively a non-starter because many features, such as background notifications, apple pay, and others, aren't available. Apple doesn't

HTML5 based apps are effectively a non-starter because many features, such as background notifications, apple pay, and others, aren't available. Apple doesn't let you install Chromium/Blink, or any other browser engine, which implements things like WebUSB and background notifications, so you're stuck with the Safari browser engine. Coinbase might have thought about it, but anyone who looks at building a PWA for iOS for any amount of time very quickly realizes that Apple has crippled it to the point of being a bad idea.