Checkbox not returning value at all

I am in the process of creating my final year project for school and am doing a order system for my family company. The part I am having problems with is the product menu and basket.

The goal is to allow the user to select multiple products on screen using checkbuttons and the program would show what is in the basket in a new window.

It seems easy but for some reason, the StringVar() is not returning any value at all. Like it returns a null value or smthn which is just empty.

it should have returned with On when the first button was clicked and Off when it was left alone. I tried using the .pack() thing but it doesnt work with grid. I have also tried using the same window but the result is the same.

this is the sample of the code where the issues are happening.

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