Is It a Flatpak? Is It an AppImage? No It's AppJail

x11appjail is a specialized tool for creating, verifying, installing, and running AppJails. An AppJail is a CLI, TUI or X11 application that runs inside a FreeBSD jail but is perceived by the end user as identical (or at least very similar) to an application running directly on the host system.

This tool makes extensive use of appjail(1) as its engine; however, unlike the latter, the primary user in x11appjail is neither root nor a privileged user, but rather an unprivileged user. The fundamental goal of this project is to grant the user limited access to the jail, restricted solely to the execution of a CLI, TUI or X11 application.

Project: https://github.com/DtxdF/x11appjail