Grouping data by email/user (Glide Pages)

Take a look at this and let me know if you have questions. The trick is to mark each row with a boolean when it’s the first occurrence and then filter a list by that boolean. That list will then show each name only once.

Then you will also need a multiple relation linking the leads table to the activity table. When you click on a lead in your list, you can display all related activities by adding an inline list sourced from that relation.