if not interested, please delete. Not meant to be spam...

I found a very interesting USB adapter....

it uses an 18650 cell and is a "usb UPS"...

https://www.aliexpress.com/item/ESP32-ESP32S-For-Wemos-For-Raspberry-Pi-18650-Battery-Charge-Shield-Board-V3-Micro-USB-Port/32901941978.html

https://www.aliexpress.com/item/2017-30PCS-set-Brand-New-18650-battery-3-7V-9900mAh-rechargeable-li-ion-battery-for-Led/32796342249.html