The app
Phantom Ramp, installed from here.
No App Store. It opens full screen from your Home Screen, tells you the moment your coins land, and keeps the dashboard you last saw readable without a signal.

What the installed app does
Delivery alerts
A notification when the payment clears and when the coins reach your wallet. Turn it on in Settings after you install.
Sign-in alerts
A notice when your account is opened somewhere new.
Works without a signal
The last dashboard and the pages you have opened stay readable. Anything new waits for the network.
The same terminal
Live prices across a thousand coins, the same data the site shows.
Updates arrive on their own
There is nothing to download again. A new version announces itself and applies on the next open.
How it installs
iPhone
Share, then Add to Home Screen, then Add. Three taps in Safari, the same way every web app reaches an iPhone.
Android
One tap on the install prompt when your browser offers it, or Install app from the browser menu.
Desktop
Chrome and Edge show an install icon in the address bar. Or point your phone at the QR code and install it there.
Not in the App Store, on purpose. The app is this site, installed, so there is no review queue between you and an update.