Most of those things are what happens by default. Sure, be careful, but by default it's secure enough to prevent most potential issues. No need to lock down file access for example, by default it only has access to files inside the container, and of course by default containers don't have access to start other containers, and so on.
Good word of caution though, make sure you actually isolate when you set out to isolate something :)
I've just discovered and started using smolmachines^1 which actually have the requisite isolation.
1. https://smolmachines.com