Add interface to each object you want save. For eg. to pawns “Enemy interface” for pickups “pickup interface”
Use those interface functions (you created them anyway) to get their locations and rotations, hp etc.
To get all actors: use “get all actors with interface” this creates array. Use that array with foreach in array loop.
You can also create EventDispatcher called “time for save”. Make all pawns and pickups register there.
When you trigger that event each pawn and pickup should add its own info to array.
For storing that data in array it is best to use structs. Each element of array may be then structure that has “location” “rotation” “HP” “type of object” etc.