The Fusion suffers from it’s weight. It falls out of an aged socket too easily. 5000mAh is enough for many situations. I think it can be improved either by same specs just smaller lighter or same physical but more powerful.
Of those options the former is my preference. Because more mAh makes it heavier, and larger batteries are well served already 10Ah upwards with the improved Powerport2.
Given they have shrunk the Powerport2 and 5 PD I think it’s viable so just wait it’s turn.
Fusion is perfect for non geeks just with phone, weekend trip just that and one cable.