The opto-FET is a device which is just a low current solid state relay.
Sometimes opto-FETs are called solid state relays.
However, the name of "Solid state Relay" actually came into being when high current and high voltage devices were made. They are expensive and big.
So if you buy one of these, the will handle many amps and can switch the AC mains supply.
So not what you need for a clock run on batteries or a low voltage power supply.
You need something similar to the one you indicated on Amazon but with the correct output.
I will have a look to see if I can find a board available with the correct devices on it.