What versions of iOS are supported by the Gruntify mobile app?
As the Administration functionality is in a Web app, you can access it using any device that has a sufficiently large screen and an up to date web browser such as Chrome or Safari. An iPad or Android tablet should work.
Are any kind of pen devices supported by Gruntify?
The Apple Pencil may be used in the Gruntify app on an iPad, both for handwriting to text conversion and for signature entry as shown in the video below