What about substituting the 10mm RGB LED with a high-power 1W (or so) RGB LED? I know that a 3-channel power LED driver circuitry between the 1W star RGB LED and the main controller (Arduino) is ...

[Fjord Carver] brings together an RGB LED and CdS Photoresistor to make a color sensor. Those Cadmium Sulfide lights sensors usually have a very wide swing of resistance when exposed to varying lev… ...

Arduino has launched its next generation of UNO boards, introducing a 32-bit Renesas microcontroller and Espressif ESP32-S3 module, one-click cloud connectivity and plenty of I/O plus a 12×8 red LED ...

You can throw a Raspberry Pi camera and OpenCV at the problem and approach it through software, or you can buy an off-the-shelf RGB sensor and wire it up to an Arduino.

Off the shelf RGB colour pickers allowing you to extract and objects RGB values can range from a few hundred dollars to thousands depending on your needs.