A date field can be used for the axis of charts in Pro. Unfortunately, it doesn't appear that the date can be formatted to a user's desire like numerical fields used as an axis. Even if it were some back-door route via the CIM, it would be great if a bit of Arcade, python, or whatever could be used to arrive at a specific, consistent formatting of dates along the axis (e.g., MMM d [i.e., no year]). See my other question post for more details on this topic: https://community.esri.com/t5/arcgis-pro-questions/can-dates-used-for-the-axis-of-a-multi-year-line/...
