I would love the option to display a dropdown list column in a sheet as either radio buttons (for single-select) or checkboxes (for multi-select). I often use dropdown list columns with 2 or 3 options, and having those options displayed as radio buttons or checkboxes in the cell would be more convenient than having to select the option from a dropdown list. And although this is a feature for dropdown list columns when using forms, using forms isn't always the most convenient solution.