I have a long driveway, and 120 v lights go all the way to end. The lights are only used occasionally. No continuous power is available there.
I’m thinking that if I hook a charger to my driveway lights, I can significantly extend the Blink battery life.
So the potential option from collected comments is:
Use a USB charger to charge a USB backup battery (~$4); so power available continuously, waterproof system (box of some sort or mount in light fixture) and use the battery USB output to power Blink.
Thank you everyone for your contributions.