DIY Front Door monitor/camera?

I mentioned in another post that I am trying to put together a mail delivery sensor and I was playing with a go control motion sensor. It didn’t work in the mailbox, so I was wondering if this is possible…

I have three CCTV cameras that are accessed via an app called CCTVvision. Is it doable, or even advisable to try and install the motion sensor at the front door, then have it send a notification to your phone when it detects motion and offer to load the app for you if you choose “yes?”

Or perhaps more basically, have it just load the app and start it on your phone when it detects motion at your front door? Am I in the realm of possible things?