@ColdEmbrace I use a combination of App Protector by Mojave Networks, Tasker, and Trigger.
App Protector allows you to password protect certain apps to run them. It also has a Tasker plugin to disable/enable that protection, so I use Trigger to run a task using the plugin.
Just note that this doesn't provide absolute protection from hackers, and theoretically rebooting the phone and uninstalling App Protector before it loads is possible.
If you're looking for protection at the firmware level, I'm not sure how.