When is Shimano Di3 going to be released? And 12-speed GRX Di2?

Di3....?

Sorry, it doesn't work that way. Di2 stands for Digital Integrated Intelligence. Of course, Shimano could add another I to that and call it Digital Integrated Intelligence Improved (Di3)… but it’s more likely that they will just increase the existing model / product codes.

12-speed GRX Di2

People have been asking me for information on 12-speed GRX Di2 for a while now, but no... I haven't heard anything that indicates it's coming in 2023. I wish, but I suppose we'll have to wait just a bit longer.. My best bet is 2024 for 12-speed GRX Di2.