This short article describes a flight-safe power supply for FieldOps.
Component List
Simply get these:
Xiaomi Pocket Power Bank Pro 10000 33W
This one does 9V, 12V, 15V and 20V without any problems.
OR
A 65W USB PD power bank - not needed for 5 to 10W QRP FieldOps
ZEB-TT60VUSB-C to USB-C cable (Zebronics 3A cable for 99 INR from DMart)
Pics

Cost
Total cost: < 2500 INR