LXD is used in Crostini (https://www.reddit.com/r/Crostini/) as a way to be able to run Linux applications in chromebooks.

In addition, Samsung is somehow using LXD in their new phones, with "Linux on DeX". In that way, you can get a Linux interface with Ubuntu when you plug your phone to a monitor/TV.

If you use a Linux desktop, you can get to run GUI applications in a LXD "system container", therefore isolating the files from your host's filesystem.

Here is how to do this by sharing the X server of the host (filesystem separation but sharing the X for convenience), https://blog.simos.info/how-to-easily-run-graphics-accelerat...

You can run things like CS GO DeathZone in such a LXD container with full GPU acceleration, and even closed-source NVidia driver.

Some people also got an LXD container to run in a separate X server, thus having even better isolation.