From the F-Droid website:
“F-Droid is an installable catalogue of FOSS (Free and Open Source Software) applications for the Android platform. The client makes it easy to browse, install, and keep track of updates on your device.”
For the reasons outlined in “Why self-host/use FLOSS?”, one should use FLOSS (Free/Libre and Open Source Software) whenever possible. The source code is available for every app on F-Droid.
ImagePipe or Scrambled Exif. Both apps are designed to remove EXIF data, metadata in photos that can betray personal information, before sending pictures. Despite serving a similar purpose, the two apps differ in implementation and in terms of features. Notably, ImagePipe also reduces image size (though it keeps the original unaltered and stores the changed copy in a separate folder), which may or may not be a desirable feature depending on use case.
KISS Launcher. I find that pinning a few choice apps and searching for the rest with KISS Launcher is a more pleasant experience relative to the default GrapheneOS launcher. Also, launchers allow one to use custom icons (I use Ameixa Monochrome).
Netguard. Block access to the internet per application. Unfortunately, I haven’t found a way to combine it with Orbot yet.
NewPipe. NewPipe allows the user to watch YouTube privately on their smartphone; in addition, the user can keep up with their favorite content creators without signing up for an account.
Orbot. An invaluable tool for privacy, Orbot tunnels the traffic of selected apps through Tor.
Termux. Termux is a terminal emulator for Android, and offers an incredible amount of power. I use Termux to securely transfer files between my smartphone and computer using SSH, and my dotfiles are there, too.
UntrackMe. UntrackMe transforms certain links, such as YouTube, Twitter, and Instagram, to point at a FLOSS privacy respecting alternative. In the case of Twitter, it changes the domain to a Nitter instance, for example.