In terms of what can be damaged, let's hope the bed bugs, for starters... ;-)
125 F is pretty warm, but it does fall short of, say, actual food cooking temperatures. That's a painfully sunny summer afternoon in Phoenix or Death Valley, but it isn't Dante's Inferno.
I can't imagine it harming cereal (unless it was also humid). But I couldn't vouch for every possible perishable product you might have on your shelves. Canned goods will be fine. They were canned at much higher temperatures than that. Things like bread should be perfectly fine. Oils like coconut oil and butter will most definitely melt into liquid at that temperature, but it isn't hot enough to change those oils chemically. I believe even olive oil should still be stable at 125 degrees and won't be altered into saturated oil.
Electronic devices should also be fine if you turn them off, then let them cool before turning them back on. Parts of most of those devices internally probably match or exceed 125 degrees during normal operation. Plastic parts aren't going to melt at that temperature. The maximum safe operating temperature for most hard drives is up around 122 degrees F (50 C). CPU's will run hot enough to cook eggs (or burn fingers). If that kind of equipment is shut off during the procedure, then you let everything cool off before turning it back on, you shouldn't have problems.
What you don't want to do is remove anything that bed bugs might be hiding in, to protect it from the heat, then take it back in the house without fumigating it to kill any stragglers, or you could up back at square one.
How long does the interior have to stay that warm to make the bed bugs expire? I presume it has to be long enough for the temperature to normalize all the way through things like mattresses and piles of bedding and such?