Most common type of surge protection component used in surge protection device is MOV (Metal Oxide Varistor) or commonly known as varistor. I can 100% sure this is used in the device you've shown. There ore other type used on PCB like TVS, GDT, and Zener Diode.

The surge protector will clamp voltage over its rating by shunting the current to the ground. Therefore varistor or any other components mentioned is connected between L and N. Varistor has its own power rating or how much energy it will absorb before it fails. So, when voltage surge happened varistor (actually stands for variable resistor) will lower its resistance thus redirect excess current from L to N to keep the voltage to device within range.

Therefore, if the current (energy) is too much and beyond the varistor rating, the varistor will fail which means it behave like open circuit. Once broken, the voltage goes spike will go direct to your device.

So, it is not about MR.DIY. I think it will sure give the protection but depends on itsrating Same goes to any brand. However, some more expensive one will have other circuitry like to disconnect the power line once a surge current is over certain limit, thus will safely protect the device in case of varistor failure.

Even the branded one like inside power extension strip, there is nothing special but just varistor. No need to be fooled by brand name.

Even my cheap Chine no brand one protect my plasma TV last time when many residents in my taman had their TV roasted

No. I do not have any recommendation because do not use one for my PC or laptop.

If you really want a good one. Need to install surge protector at incoming DB box too. For the socket one either in for of multiple socket extension, just buy any good known brand. It should be okay. The laptop is using external PSU. Inside the PSU also got surge suppressor too. Maybe he PSU get damage first before the PC/laptop I guess.

RCCb and ELCB only protect what you mentioned. I was talking about surge protector. Well they will also trip when power surge like lightning but after your electronics devices kaput. Good i=one has response time in nano second. The millisecond one cheaper but will not able to protect sensitive electronics stuffs.