Software alert when doorbell rings. Doable?
Take a 110/220 Vac small table lamp, or one of those with clips, that allow you to attach it to thin surfaces. Put it behind, or next to your laptop screen, so that you unavoidably see its light, when turned on. Take a pair of long wires, and connect the lamp in parallel with your doorbell (assuming it is mains powered). That should be the easiest :-)

Even if the actual solenoid is fed with a lower voltage, in many cases (in Spain, all the ones I know are like this) the pushbutton still switches on/off the mains voltage. So, take the voltage from the doorbell box, but from the primary winding of the transformer.

And, if the pushbutton switches a lower voltage, use a lower voltage lamp. The idea is the same.