For a complete mobile server solution, you'll want to add a rechargeable LiPo battery and on/off switch to the Feather. The simplest switching solution is to use the Enable pin on the Feather.
You can also 3D print a case to neaten it all up. Or just put it loose in your pocket or backpack.
Use two short wires to solder the switch to the Enable pin and GND pin on the Feather. When these are shorted, the Feather will power off.
Insert Switch, Feather, and Battery
Insert the switch into the case and screw on a hex nut to secure it.
Connect the battery to the Feather and then add them to the case.