NOTE: You can also restrict the repository, for example "only free libre open source" or "only verified apps". The Librewolf Flatpak is verified, so you can use the subset:
flatpak remote-add --subset=verified flathub https://dl.flathub.org/repo/flathub.flatpakrepo
# or when already added, check if all your apps are verified, or they don't get updates!
flatpak remote-modify --subset=verified flathub
# to remove the subset:
flatpak remote-modify --subset= flathub
To install LibreWolf permanently via an AppImage, we recommend
AppImageLauncher.
With AppImageLauncher installed, you just need to open the AppImage with
AppImageLauncher and click Integrate and run. LibreWolf should then be
permanently installed on your system and launchable via the application menu.
To update or uninstall LibreWolf from your system, you can just right click the
LibreWolf application menu entry and click either Remove AppImage from system
or Update AppImage.
After pressing the update button, the whole update process will be completely
automatic and you don't have to do anything else.