I’m about to install bazzite on my wife’s older (2017) Windows 10 machine, and I’ve been going over how to recreate everything she currently has. Most programs (even proprietary ones) are not an issue, but I’m not finding much in the antivirus department.
I never even thought to install one on my Linux machine (also on bazzite, but I have used other distros in the past). So although I am no stranger to Linux, this issue blindsided me.
I know clamav exists, and I’m educating myself on how to use it, but a GUI would be nice for the wife. She’s not afraid of the terminal, but she likes the convenience of GUI programs.
Any suggestions? What do you use? Or is it just generally accepted that one should be careful and keep things up-to-date and that’s enough?


AppImages have no sandboxing as you said. They also rely on the deprecated SUID-root binary FUSE2. AppImages are bad for security but they are convenient. A malicious AppImage could for example connect to org.freedesktop.secrets and access your keychain, or run a script that places a script called “sudo” in $HOME/.local/share/bin that is preferred over the real sudo and logs a password, or encrypt your files in a ransomware attack, or exfiltrate your session cookies from Firefox or Chromium browsers.
Flatpaks on the other hand are sandboxed. IIRC Flatpaks can’t access other Flaptak’s data folders in $HOME/.var/app (maybe even if home access is given?), but if given access to the “home” permission they can read and write to anywhere else in the user home, so stealing session cookies from a browser or ransomware could still be possible given the right permission. Modern apps that are designed to work as Flatpaks can use the xdg-desktop-portal to access only specific files/dirs upon user request, but it is only temporary access to a file. All the ways a Flatpak can access the system are defined by its permissions, so by giving more/dangerous permissions (such as devices or full filesystem access) a malicious app can possibly escape the sandbox and access arbitrary permissions. The worst permission an app can have is access to session bus for org.freedesktop.Flatpak, which allows it to arbitrary permissions, host command execution, and access to Flatpak configuration.
There is more to xdg-desktop-portal than I said, it is quite powerful.
https://wiki.archlinux.org/title/XDG_Desktop_Portal
https://flatpak.github.io/xdg-desktop-portal/docs/
This Flatpak shows the power of portals on your system, while also requiring no permissions at all: https://flathub.org/en/apps/com.belmoussaoui.ashpd.demo
Same with this one, but it requires arbitrary permissions: https://flathub.org/en/apps/xyz.tytanium.DoorKnocker