I've only had a smartphone for a little over a month, but here goes.
Using the Duck on Tor on an
Android phone, I accessed CCF website.
The hamburger button on the bottom of my screen does nothing in reference to an app.
However, the 3-dot menu button on the bottom of the website part of my screen brings up a menu. In this menu, there's a slider button to enable or disable the desktop version of the CCF on my phone. The slider button turns
magenta when enabled and
gray when not enabled. The desktop version-not-enabled version of the website
isn't an app. It's merely cell phone-friendly format and functionality, which I suspect the software used to create, maintain, and run the website, and/or the hosting site, and/or my phone software does without my seeing it happen. No real difference when not logged in, but a huge difference when logged into CCF.
The settings button inside the three-dot menu button brings up yet another menu, No app there or inside anything on this menu.
I checked GooglePlay and found no CCF app.
My conclusion is that there isn't a CCF app. However, there is a cellphone-friendly version and a desk-top friendly version, which appear to only affect display and functionality on cell phones, and maybe tablets, vs. desktops.
FWIW, an app is a separate beast than a website. Here's a detailed explanation of the differences
Web Developers vs App Developers: The Ultimate Showdown