Hi! Here are a few suggestions, feel free to add to this thread.

1/ Ability to destroy a building that you own.

2/ Having access to portrait and unit sprite and skill icons to change/modify them. I'm tired to see the Unity assets honestly ^^

3/ If 2/ isn't available, a "change look randomly" or any character visual customisation.

4/ Colourblind mode option: Using White/Black/Red/Blue for any colour code in game.

That's it for now, really had fun so far, so keep it up!