Devices named AO... are made by Alpha & Omega, not Vishay.
According to the schematic and parts list, that device is a P-channel MOSFET with a guaranteed RDSon of 19 mΩ at VGS = 4.5V. There are many devices that should be suitable:
There are many other suitable devices available from Digi-Key and Mouser, but P-channel MOSFETs are not generally available from small suppliers. If you tell us your preferred suppliers, we may be able to find something suitable there; otherwise, buy something from Digi-Key or Mouser.