The feature request I would like you to consider implementing is for me to be able to set those field lengths on the back end with either a universal selection for a field group by setting all fields to 100% width for mobile within a viewport size range or to be able to adjust the field width individually for responsiveness. This especially for mobile viewports. Though not a solution for all ACF Pro users, but maybe having an added plugin or a feature that can be turned on in the pro version of your plugin is to be able to do this within different page builders. I currently use Elementor pro as my page builder and I know many people who use Elementor pro also have ACF or ACF pro as a plugin they use to help create custom post types. Having something specific to help people who are weak at coding, but would like to be able to make their forms look better and be easier to fill in would love an added feature like that either connected with there page builder or something they just have to edit in either their field group or to individual fields. You could make it so you could enter the viewport dimensions and then the field width at those dimensions. You could also make it so you can add another set of dimensions with an "add dimensions" button for either a field group or for an individual field.