I am surprised that no one has make a fan assisted rebreather of some sort...
I did some work with a fan-assisted rebreather designs for bailout systems for sat divers. The engineering requirements were much deeper (500M/1,640'), on HeO2, and shorter duration than recreational rebreathers.
I wouldn't be surprised to see "blowers" as an option as battery technology improves but there is a downside besides weight, complexity, and cost — noise.