There is no LSP.expert app, but the website is responsive, meaning that it adapts to the screen on which it is opened.
To easily access the LSP.expert website from your smartphone (or other device), you can add the LSP.expert icon to your screen. You then just have to click on this icon to access your LSP.expert account (and it's just like an app ;-))
How to add the LSP.expert icon?
Apple:
Open your Internet browser on your device.
Navigate to the LSP.expert website.
Tap on the Share button at the bottom of the browser window. It's represented by a square with an up arrow.
The iOS Share Sheet will now appear, overlaying the main browser window. Select the option labeled Add to Home Screen ("+" button).
The Add to Home interface should now be visible. Edit the name of the shortcut icon you are creating. This text is important: It represents the title that will be displayed on the home screen. Once you are done, tap the Add button.
You will be taken back to the home screen, which now contains a new icon mapped to your chosen web page.
Android:
Open your Internet browser on your device.
Navigate to the LSP.expert website.
Touch the overflow button (three vertical dots) and select Add to Home Screen.
Touch Add and the site will join your other apps and widgets.
To customize the text below the icon, just touch the text inside of the Add to Home Screen box and change it up.