Nightly GNOME Apps
Flatpak is a great way to safely install the latest development version of GNOME apps, alongside the regular stable versions. This is an easy way to test the next GNOME version.
These applications are by nature in an unstable state. However, they should be always able to run and perform basic functionality. Most commonly, they are working with full functionality and just with increased stability issues. However we cannot yet ensure basic stability across the whole platform, although we are working on a CI and deployment pipeline that would ensure its basic stability.
On the meantime, you can use the stable applications and install them in parallel to the nightlies in Flathub.
Setting up GNOME nightlies
1. Install Flatpak and Flathub, following the standard instructions
2. Add the gnome-nightly repository, which provides the nightly GNOME runtime. Execute in a terminal:
flatpak remote-add --if-not-exists gnome-nightly https://nightly.gnome.org/gnome-nightly.flatpakrepo
Installing and running nightly apps
Once nightlies have been set up, they can be installed and run like any other Flatpak application. This includes installing them with Software or from the command line (see the Flatpak documentation for an overview of common commands).
Some useful terminal commands for nightlies include:
List all the apps in the nightly repository: flatpak remote-ls --app gnome-nightly
Install a nightly app: flatpak install gnome-nightly org.gnome.Epiphany.Devel
Run a nightly version: flatpak run org.gnome.Epiphany.Devel//master