My current means of powering things is USB rechargable batteries. I have a about five of them that range between small 3000-5000mah ones to a big 20000mah interstate battery jump starter pack. Is there a device that lets me add all their power together into a centeral power source so I don’t have to keep swapping them out?
no. there are chargers that allow multiple USB powered devices to charge at once but there’s nothing that allows disparate USB power sources to discharge at the same time/share a load.
your best bet would be to ditch all of the USB power banks and get a single power station with 200+ watt hours (jackery, etc - bunch of different brands these days)