This can power devices the size of a finger, and the tech is way less powerful than lithium ion

has developed a new type of nuclear battery called a perovskite betavoltaic cell (PBC), which could power small devices for decades without the need for recharging

Title lacks that key bit of information, small devices. You are still going to need to change your phone. And small devices can already last for years on conventional batteries. So the win here is minor at best if it ever actually sees the light of day.