I haven't found a working out-of-the-box solution for the color picker, so I decided to make one.
I've tried to implement it using bindings, but it didn't go well, so it uses a separate script to populate data.
Help is much appretiated.
References:
https://github.com/plyoung/UIElements
https://www.youtube.com/watch?v=MOiXqKFHAIs
https://github.com/Unity-Technologies/UnityCsReference/blob/61f92bd79ae862c4465d35270f9d1d57befd1761/Modules/UIElementsEditor/Controls/ProgressBar.cs
https://docs.unity3d.com/2022.3/Documentation/Manual/UIE-bind-to-nested-properties.html
https://discussions.unity.com/t/solved-how-to-force-update-visual-element-on-the-current-frame/754305/7