I use this Xiaomi MI powerbank :https://www.gadgets4geeks.com.au/xiaomi-20000mah-mi-power-bank-3-dual-usb-type-c-power-delivery-fast-charger
It “only” charges 45W (15V 3A)
This weekend I used the PPM on presentation mode, using the internal S-youtube app, connected to the powerbank.
After 3 hours we were done, and it still had juice (I did not check how much though).
The image was brighter (as if connected to the mains adapter), but it might have shifted to lower brightness at some point without me noticing…