Wildcard Arrays on Data Asset Types

After looking through the gameplay feature plugin, I found the action input drop down inside of Game Feature Data (Data Assets that are created when you make a game feature plugin). That interface seems to have an array of objects that have different parameters exposed in each of them.
The ability to have an array of a variable strut (or exposed object parameters) seems incredibly valuable to make flexible modular systems. Lyra seems to be using this in a couple different systems (where I originally found out about this).

In C++, what is controlling when these variables are exposed? Is there any way to recreate this interface in blueprint? I’m open to any recommendations on creating something like this.