ordinary power strips protections for power outlet IOT
Normal surge protectors are 3 MOV's (Metal Oxide Varistors) between Live - Neutral, Live - Earth, Neutral - Earth, as well as some Y2 class capacitors in parrellel with the MOV's thrown in to soak up some of the mains noise to keep smaller spikes from tripping them

e.g. if your area is 240V mains, you might use 275V MOVs to clamp surges, just be aware that they can only survive so many surges before they need to be replaced

The fancier ones include a circuit breaker that can be reset, the good ones break both live and neutral, the ones you usually see for lower costs only break the live wire.

Some of the active surge protection circuits you showed may be better alternatives, however relays are usually much slower to switch than a surge that may damage things, that would be more for areas where prolonged brownouts or higher than spec voltages are expected for say half a minute or longer,