Both rated for 120v. Still not sure on make and model management is behind on ordering them.
Not the voltage - the wattage ( or the amperage).
A typical washing machine may, when heating water, consume 2kW (or more). A dryer can run to 3kW. Add in a dish washer may be around 1.5kW. Total for BOTH operating would be 4.5kW and, with allowance for 'extras' round up to 5kW. 5kW at 120V is over 40amps..... a 50A or 63A switch would be needed and the cable feeding the switch/socket suitably rated as well as the main MCB in the distribution board.
How are the devices to be attached to the power supply. They normally come with plugs attached so two socket will be required. If they are just hard wired into a single switch (not a good idea) then that switch will need to have the ability to safely take two cables - no switches that I know of have this capability.