Which Cryptocurrencies Have Implemented the Proof-of-Activity Consensus Model?

Decred is the most well-known cryptocurrency that utilizes a hybrid consensus model similar to Proof-of-Activity. While Decred's model is often cited as a prime example, it's a customized version that combines PoW and PoS.

The original Proof-of-Activity concept has not seen widespread adoption, and very few, if any, other major cryptocurrencies have implemented it in its purest form. The complexity of the model and the dominance of pure PoW and PoS systems have limited its use in the broader cryptocurrency market.