Design and Component Selection (or Sourcing) of a USB Switch

All inputs and outputs are USB-based and operate at 5V. The power requirement for the computer and its display is 24W. We urgently need a solution for a demo set of 30 machines. Additionally, if it can also serve as a long-term solution for larger sets, that would be ideal. However, price and speed are currently the most important factors. We need a USB switch that can: Cut off power supply from the backup power source to the computer and its display, preferably using a mechanical toggle switch. Furthermore, it would be preferable (but not necessary) if the switch can EITHER: Cut off power supply from the backup power source to the computer when external power is charging the backup power source (or cut off external power supply to the backup power source when power is being provided from the backup power source to the computer, although this is a less favorable option). OR When receiving external power, directly supply it to the computer and charge the backup power source, but not provide power from the backup power source to the computer. This solution would be the most desirable for the long term, but if it requires replacing the power bank and external charger, their selection should be part of the project. It's unlikely that we can pursue this option for the demo set due to cost and time constraints. If the solution is easy to assemble and test, we can do it ourselves. If it's a more complex project, you should assemble and test one unit.