Make a USB-C charger powered by an 18v RYOBI battery : r/ryobi
Ryobi One+ 18V USB Power Adapter - Skin Only - Bunnings Australia
P743 USB Battery Adapter Camping Light,Hipoke Portable Power Source Adaptor 420LM LED Work Light Dual USB Phone Charger with Hook Compatible with Ryobi 18V One+ Li-ion Battery: Amazon.co.uk: DIY & Tools