Depends on how well the canister insulates it. Steel conducts heat fairly well; it'd get hot inside but I'd guess some airflow around the canister would probably keep it from getting hot enough to cook the electronics. (definitely don't take my word for it lol)

Phones are very low power, likely just a slightly warm spot on the can that radiates, conducts, and convects the heat out. You could also use one of those peltier module phone coolers, to ensure the heat gets out of the phone and into the air faster.