The obvious precedent for variable-pitch blades are variable-pitch propellers on aircraft and helicopters. I don't want to say it's a solved problem for turbos, but there is almost a century's worth of prior art on the topic. That's one of those things that (in hindsight) really makes you wonder what took so long to think up.
Because it has to be cheap and reliable at 1000*C for 200,000 miles over 10 years while constantly accelerating to 280,000RPM and decelerating with no oil or cooling air circulating when the car is stopped. https://garrett.honeywell.com/products/how-a-turbo-works/
Variable geometry turbos are a thing, and have been for some time. The larger trucks and semis use this technology. Typically they are hydraulically controlled.
That's a challenge, but the thing is a turbo deals with blazing hot exhaust gasses just out of the manifold. A prop is still a marvel of engineering, but it doesn't need to be made of boron carbide to not melt.
A better comparison would be variable pitch vanes on jet turbines.
https://en.wikipedia.org/wiki/Variable-pitch_propeller