There are more to RGB than just colored coins. It's a system to allow state transition for layer 2 and 3 and beyond.
If you search LNPBP Standards Association on YouTube they have monthly updates on research and development.
Yes, that’s a good resource as well as rgbfaq.com. However, it seems it’s only Dr. Orlovsky working on it more or less alone. It also appears he has other projects so the pace of development is quite slow in addition to it being a complicated protocol.