Keep it simple

Strategic mastery right there

Jacksonville!!!

The best kind

Well wrought iron melts at 1500C, brass and bronze around 1700C. And it would take considerable time at those temps so probably not just 1 cast of the spell. Also Burning Hands is a cone, so at those temps anyways it'd assuredly melt stone walls and floors, set fire to the door, roof, and anything else.

Some Object properties: Iron/steel has an AC of 19, irrelevant since it's a Dex save, and a lock has 5hp. But since it's probably immune to fire damage of this temp, the lock may very well be the only thing that remains after Burning Hands sets everything else ablaze. And the door probably has ~18hp, so 1 burning hands won't obliterate it, but the ongoing fire damage after it's set aflame likely would. Though the roof would probably go first.

I mean a door has HP. Burning hands would definitely damage it

If you burned a sorcery point with shape spell, I could see turning it into a temporary blow torch, but it still only lasts the one action. Even heat metal doesn’t melt things (except lead or aluminum which melt before they get “red hot”), but it would probably burn the wood around it or weaken the lock enough that it would bust if the door was rammed.

If violence wasn't your last resort, you failed to resort to enough of it.

—The Seventy Maxims of Maximally Effective Mercenaries, maxim 7

But also:

Pillage, then burn.

—ibid., maxim 1

Nice try, Megumin

The solution is to make your players afraid of a well-practiced DM that knows how to fuck with powerhungry wishes.

"I wish for an invincible unassailable fortress"

it appears... and then falls directly on top of the player

"I wish for true immortality where nothing can kill me ever ever ever"

granted... in a pocket plane with no way in and no way out

"I wish the final boss was already dead""

player is time-skipped to a far future where the boss is dead and so is everything in the campaign they know or care about

To ensure the factor and keep the wishes reasonable, be sure to insist that the wish magic must be spoken out loud, without pause, and more or less be a single sentence like in almost every example given of wishes in antiquity fiction.

The wish works but there is a nearby weapon manufacturing district. The weapons from the warehouses suddenly appear all around the players. They now have to crawl over a giant pile of pointy weapons. And, the gold landed on the bottom of the pile out of reach.

I think we can also accept fireball

The shitty part is that last I checked fireball had no explosive properties apart from "rule of cool" from DMs that want it to have explosive properties. It was a dinky little glowy point-and-click dot that goes fwoosh, does fire damage, then vanishes.

I think that's ridiculous, but a rules lawyer could shoot down the fun unless that changed when I wasn't looking.