By default, Lubuntu does not come with Flatpak support enabled, however the necessary packages to do so are present in the Ubuntu repos and enabling the use of Flatpaks is very easy on Lubuntu.
Disclaimer: Flatpaks are provided by third-party distributors that are separate from the Ubuntu ecosystem. Ubuntu has no control over the Flatpak software repository. We cannot provide support for software downloaded via Flatpak.
To install Flatpak support on Lubuntu, simply run the following sequence of commands:
sudo apt install flatpak
flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
Then reboot your system. This will allow new Flatpak apps to appear in your application menu.
You can now install apps via Flatpak from the Flathub repository. Flatpaks often have somewhat odd names, so it may be tricky to simply “figure out” how to install a Flatpak. Instead, you can browse Flathub in a web browser to find the command to run in order to install a desired app.
For instance, if you want to install KDE Keysmith (a 2FA application), you can search Flathub for “keysmith”. You can then click on the application in your web browser to open its info page. At the bottom of the page, you will see a “Command line instructions” section with the commands for installing and running the desired app. For Keysmith, the correct command is flatpak install flathub org.kde.keysmith.
Once a Flatpak is installed, you should be able to find it in your application menu. If you can’t find it, reboot your system and it should appear.