@Fuseteam I think @pparent is right, that it is currently unfortunate, that new users will open the terminal on a fresh Ubuntu Touch installation and will be confused that apt gives an error message. And it is also kind of clunky to set up a libertine container first.
If his proposed solution is not feasible, maybe the terminal could open a window like "Hey, apt is not the default package manager on Ubuntu Touch. Please use crackle, snap or a container solution instead." when it detects, that "sudo apt..." is entered. This would be a little bit more user friendly.
On that note: Are their any plans to make crackle a default system program or to make crackle installable over the Open Store?