“Useful” Proof-of-Work? Seeking Existing Projects

I’ve been thinking about how Bitcoin’s proof-of-work burns tons of energy just on hashing. What if we used that same brute force to do something valuable, like matrix multiplications for large ML models or protein folding, withoutcompromising the key PoW features (easy verification, randomness, etc.)?

Has anyone come across a fully decentralized project that’s actually doing this? I know of Primecoin, CureCoin, and a few distributed computing platforms (like Golem), but none have scaled to Bitcoin’s level. If you’ve seen papers, code, or live projects on “useful PoW,” let me know. Thanks!