I'm 90% sure an app for SaSu does not exist. Perhaps a mod could confirm?
Though I'm not a mod. The video below is recorded on Windows, but the app is available to me on my Android phone too.
On Windows 10, I use Brave (version 1.65.122 Chromium: 124.0.6367.82).
On Android 11/12, I use Brave (version 1.65.114, Chromium 124.0.6367.60).
View attachment ss-app.mp4
if anyone has the app, how is it?
It's exactly the same as the website in your browser. The "app" is more of a wrapper around the website to allow you to open the website directly from your home screen. You're not missing anything as far as I'm aware.
A similar solution is to use the "Add to Home screen" option on Android (Chromium browser) or to create a shortcut file to this website URL on Windows and change the icon to your liking.