Lenovo USB-C PSU for laptops powers a Rasberry Pi, but cannot simply charge bicycle lights. WTF?

https://lemmy.sdf.org/post/52444164

In addition to what others have said, I would hazard a guess that these bike lights shipped with a charger that uses a 5V brick and a Type A to Type C cable.

With A to C, no negotiation happens - 5V just gets sent.