For what it’s worth, I wish I had this feature on my garage fridge. It’s getting older and sometimes the door just doesn’t close all the way. Because of the way my house is laid out, you can only hear the beep if you’re in the kitchen (and even then it’s not very clear) so it might sit open for hours before being noticed. Granted, this feature is definitely not worth buying a smart fridge and I probably wouldn’t want one in my garage, but I wish I had something to fix that problem.
If the other tips don't work you could add an smart powerplug that measure the consumption and then figure out what pattern you have when it is open and then send an email or sth. (I hope such power plugs exist)