In tkinter, is there a way for me to reference a widget within a grid by its row and column, in the same way that you would be able to reference an item within a list (or list of lists) by knowing its position in the list?
You can call the .grid_slaves(row, column) method on the parent widget; this will return a list (possibly empty) of the widgets in that cell.
You could also iterate over all of the child widgets (.grid_slaves() with no parameters, or .winfo_children()) and call .grid_info() on each one.  This returns a dictionary with 'row' and 'column' keys, along with various other grid parameters.
Find an item by its position in a grid tkinter