Risk from transients (ie lightning) is defined even by geology. Surges that do damage are hunting for earth ground. If that transient is not connected to earth BEFORE entering, then nothing (as in nothing) will protect from that surge.

Defined by their spec numbers as 'nothing' include products from Furman, Surgex, and other magic boxes with spec numbers that do not even claim effective protection. Honest protection is recommended by citing spec numbers.

If interior appliances are creating surges, then one is replacing dimmer switches, GFCIs, clocks, cash registers, LED & CFL bulbs, and fire protection electronics (ie smoke detectors) daily. Those rumored surges are only noise. Typically a few tens of volts or less. Noise damages no appliances.

View numbers for magic box protectors. Many will list the let-through voltage - ie 330 volts. That means it does absolutely nothing until 120 volts well exceeds 330 volts. It completely ignores and does nothing for noise from appliances.

120 volt electronics were required to withstand up to 600 volt transients without damage. That standard existed long before the IBM PC existed. Today's electronics are even more robust.

Your concern is that transient (maybe once every seven years - destructive surges are quite infrequent) that can overwhelm what is already best protection at appliances. That means properly earthing a 'whole house' solution - to every wire in every incoming cable. Only then is best protection already inside appliances not overwhelmed. Then hundreds of thousands of joules harmlessly dissipate outside. How many joules does that magic box claim to absorb? This best solution typically costs tens of times less money - ie about $1 per protected appliance.