The project was very successful. Temperatures hover about fifteen degrees above ambient temperature, and I hope my seeds will germinate.
Next time I do this, I think I will use an Arduino with a servo and a temperature sensor to automatically close and open a vent on the cardboard box for better temperature regulation.
The main goal of the project is also successful. Although my computer is slow and old, I'm still able to contribute points to the Hackaday team in humanity's fight against COVID-19.