Could one of the LibreTime developers please consider porting it to Sandstorm?
Sandstorm makes applications like this very easy to get running in a secure environment.
Have a look at the live demo of Sandstorm here and see what I mean:
https://alpha.sandstorm.io/
(Choose “Install from App Market”.)
To have LibreTime included in the AppMarket, there is a brief tutorial here:
https://docs.sandstorm.io/en/latest/vagrant-spk/packaging-tutorial/