There are a few things I would love to see in the saving/loading system:
1. Check if a save slot exists by name.
2. Delete a save slot by name.
3. Read save slot data without loading the state. So I can parse the json and read data about the slot to show in the loading screen, such as selected difficulty, game time, progress percentage, screenshot, etc.
Or alternatively give the ability to attach custom strings to a save slot when saving, which you can later on read with new actions without loading the actual state.