FiiO M3 Pro? https://www.amazon.com/FiiO-M3-Pro-Resolution-Touchscreen/dp...
> 15 hours battery life and 35 days standby time: Adopt 1000 mAh high-capacity lithium-ion battery and USB-C charging technology. The M3 Pro has a battery life up to 15 hours and standby time up to 35 days. That means if you listen 3.5 hours every day, the M3 Pro can go for a whopping 1 week before needing to be charged again!