"Windmills" and electric cars do not, in fact, rely heavily on rare earth materials. Enormously more are used, e.g., in quadcopters. Even in places where powerful rare-earth permanent magnets are now important, they will soon be largely displaced by nitrogen-iron magnets, which are both radically cheaper and more powerful.
Google data centers are not examples of a "green energy transition".
There are so many years since commercial iron nitride magnets have been promised, but none have appeared, that I doubt that they would appear any time soon.
Like for many other inventions, it is likely that commercial iron nitride magnets would have appeared only if the original patent holders, who do not seem able to solve whatever technological problems exist that prevent their use, would have published which are the problems that block them and would have been willing to license the patents in advantageous terms to those able to solve such problems.
From the little published information it is not clear whether the iron nitride material is too difficult to produce or whether the crystalline structure is unstable in time, leading to a short lifetime.
Google data centers are not examples of a "green energy transition".