The script on the computer checks to see if the smart plug is on or off. Depending on the state, the script blocks or unblocks the websites. The smart plug is just acting as a button that is connected to your WiFi.
True, I might just be inventing a problem for a solution. Maybe it would be useful for rugged long-term trekking situations, but with the size and efficiency of solar, that might not even be necessary either.
Digital displays draw a lot of energy, and need to be bright enough to be visible in direct sunlight. A more advanced version of this could increase the battery life of a camera substantially.
I'd suggest using checkboxes instead of radio buttons for the operator selection. It would be useful, I think, to have a mix of just addition and subtraction, or just multiplication and division, instead of having one option or all four.