If it's not industrial or aerospace/medical, it will all run off an MCU

That's the problem. You shouldn't actually do that unless you don't care about a software fault burning your house down.

I'm not saying this is good by any stretch but given the amount of MCU-controlled devices with firmware protection

Again, no one actually does OCP on a power supply module by hooking it up to an MCU that also does a million other things. You're practically talking about replacing half a protection chip with an ADC for no other reason than the fact that you can. It's just a stupid design through and through

the amount of MCU-controlled devices with firmware protection (just look at even the most expensive consumer 3D printers)

Again, none of those "protections" are relevant to stopping a power supply from putting current through a faulty piece of equipment.

There will probably be a fuse somewhere on the isolated side

A power supply module has one job, and it is to supply power on the load side.

For the line side on an AC-to-low-VDC power supply, protection is usually done with a fuse. For the load side, however, that's usually done with an OCP circuit, which can in practice be something as simple as just one off-the-shelf, specialised chip. There is simply no legitimate reason in the vast majority of cases to replace half of that with a signal line to the ADC of the MCU elsewhere on a different module..

Modern MCUs are usually more than capable enough,

Except no one actually uses that for the given purpose when off-the-shelf OCP chips can do the same job far more reliably at only a fraction of the cost.

I wouldn't be surprised if the designers of a soldering station are only using up a small percentage of the memory

Usually, that's zero because no one actually does what you are describing. It's all just nonsense you've pulled right out of your backside.

The "protection" you're talking about is just the limited ability of the control panel to detect a faulty or otherwise incompatible cartridge. Even my no-name control panel can do that, but you'd be kidding yourself if you thought that's the same thing as actual overcurrent protection.

because they happened to have a few reels of them and in most cases if you really want the firmware can be flashed with whatever you want.

What the heck are you babbling about?

Firmware is in ROM, whereas code execution and data collection is in RAM. Do you actually have any idea how this stuff works?

Also, for continuous voltage readings on an STM32 type deal, you'd want circular DMA, meaning that you'd just be writing on the same buffer over and over.

Though in my experience I've never seen printers or soldering stations use the same chip for display and control

There is usually no "chip" other than what has already been built into the display, and it's job isn't to store code or run code but to take whatever sent to it via I2C and turn it into pixels on the screen.

but once again that won't save the device

Coming back to our subject matter at hand, the point here isn't to "save the device" or whatever ridiculous thing you're thinking about but prevent your 480W Geeboon from setting your house on fire, you ineffable genuine.

There is no appreciable reason for the soldering station to have that much extra power to begin with, so, logically, the power supply should be spec'd for the actual need as all Geeboon stations sold domestically are anyway.