I’ve seen COTS adapters which connect to a standard phone jack with pass through and provide one USB port, advertised as an emergency/backup power. I don’t know

I’ve seen COTS adapters which connect to a standard phone jack with pass through and provide one USB port, advertised as an emergency/backup power. I don’t know how much power they can draw, however. The one I’m familiar with is called: VR3 (brand) Phone Jack Powered Emergency Night Light & Charger (model: PJNL-USB)