Biden was actually fairly committed to the student debt forgiveness, but his blind institutionalism meant he couldn’t actually achieve much. He wouldn’t push to remove the filibuster until late into his presidency and refused to discuss stacking the court. He was the wrong man to meet this moment in history, and we’ll be living with his failures for decades.
Democrats never had near enough seats in Congress to actually expand the Supreme Court or remove the filibuster. He said he would support it but if he would’ve said more than that you would be blaming him for not accomplishing that also, even though it was never possible.
There were procedural methods they could have used to eliminate the filibuster, which he refused to even consider for half his term. They would have needed the House to expand the court, but if they had the balls to do it, then they could have run on it. Instead, they tried nothing and got nothing.