Hello,
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UWP has a lockscreen namespace but it is used to create an app that acts as the lock screen, allowing greater user personalization. You can develop novel unlock gestures and animations, and also display custom information or appearances for people.
For the second requirement, currently, UWP does not have such API could restore the files that have been deleted by the user.
So UWP might not be able to meet your requirements.
Thank you.