As another accurately noted, that safety ground in a receptacle does nothing to protect hardware. It exists to protect humans.
Protector adjacent to an appliance does same near zero protection with or without a safety ground. Anyone can read those specification numbers. Most don't.
How does its hundreds of joules 'absorb' a surge that is hundreds of thousands of joules. Obviously it doesn't. How does its 2 cm protector part 'block' what three miles of sky cannot? It can't.
A protector adjacent to appliances does almost nothing to protect hardware. And can even compromise what is better protection inside an appliance.
Something completely different (called a surge protector) means everything has protection. This completely different device does not try to 'block' or 'absorb' a surge. It must do protection even from direct lightning because it has the one item that only effective protectors have. A low impedance (ie less than 3 meter) connection to earth ground. Not wall receptacle safety ground - earth ground.
Voltage variations are irrelevant to electronics. And problematic for motorized appliances. Meanwhile, all protectors ignore those voltage variations. Again, anyone making a conclusion without first learning numbers is asking to be scammed.
A protector typically has a 330 let-through voltage. That means it does nothing until 120 volts well exceeds 330 volts. Where is the voltage protection? It is created by myths and lies in advertising. It markets to consumers who do not always demand and read spec numbers.
What is the best protection from voltage variations? It is required and already exist in electronics.