Enable alternative text field for attachments added via ArcGIS Pro

[EricaNova]

I created a feature class in ArcGIS Pro and added attachments in Pro so I could bulk-upload them. Currently, AGOL does not support this functionality (ArcGIS Online currently does not allow batch-add for attachments).

When I manually add an image to a record in AGOL, I can add alternative text; there is a custom field here. See:  https://www.esri.com/arcgis-blog/products/arcgis-online/mapping/configure-pop-ups-tips-photos/

However, there is no alternative text field for the attachments I added in Pro. This is an important accessibility feature that is missing. Ideally, an alternative text field would also show up in my configure pop-up window, and I could use an expression or field to fill it.