How to add custom global style options like accent colors?

[ohfuchs]

Hi, I'm currently creating my first FSE/block based theme.

I'm wondering what would be the right way to offer custom global style settings to the user? for example one or more accent colors?

The Styles section feels like the right place to me, but I could not find any information about how to add custom options here (like on the right)?

theme.json feels like the right place to put settings like these, but "styles" seems to be restricted to built-in styles.

{
    "$schema": "https://schemas.wp.org/trunk/theme.json",
    "version": 2,
    "styles": {
        "color": {
            "text": "#000000",
            "accent": "#00ff00"
        }
    }
}

It is important to me to have settings in a global, non-block based scope.