So, both of your criteria's are easily achieved... You can easily do this with a simple NVR & PoE camera system. There are many systems out there & many in my opinion are subpar (camera quality & features), but budget dictates the quality of the system. Full disclosure I work in the industry & design & install security, automation & network systems... I personally use a locally networked NVR & cameras at our properties... I do have the NVR setup to send alerts. This is different then many systems (the rings / google / tons of others)... your system is closed & locally stored but the system can send you alerts of captured events so you can login locally to view them.
Much of what has been said is true... Cameras / notifications are after the fact... (i.e. something has already happened) but these events are relevant in your case. If a package is delivered you are notified... then if there is another event (package is taken) you are notified... this sounds like what you are looking for & is easily & reliably accomplished with no monthly charges or being directly tied to the internet. I'm not really comfortable calling out brands / manufacturers as we are dealer for some of them but I would stay away from the Amazon / Google / etc owned products... they are marketing companies not security companies.