Unfortunately, the system lock screen is impossible to overcome except for either rooted devices or integrated apps, installed by manufacturer or cell provider (though, some companies may have their corporate apps installed by manufacturer as well with root-like privileges, which might include lock screen overriding). So, that must be out of scope for a third party public app.

Will try to make an overview of my sling solution on weekend.

The "proof of concept app" need to wait for a couple of weeks to free up some time for it.