My RV fridge has no mechanism to prop open so that it does not get nasty inside.
This little piece fits over the latch plate on the top of the door and provides a stop that keeps it ajar and a translated latch to keep the door from opening more.

It works for a left hinged door but you can mirror in your slicer if your hinges are on the right.

I designed it in FreeCAD and uploaded the model. Hopefully that works for you if you want to remix it.