Bit of a different direction here: if this is a well known brand, replacement keyboards can be dirt cheap, and are super easy to replace. Big refurb.and used space for these parts as well.

Solved! I had to swing by a hardware store for some screwdrivers and bemoaned a few secret screws keeping the thing from opening, but I located the keyboard ribbon and removed it. All is well! I even gave the fan a little cleaning, which was long overdue eheh. Thanks folks!

Are you using the working keys on the builtin keyboard?

It would be great to find a software solution.

A hardware solution would be to unplug the keyboard if you are always using an external keyboard. As long as it will bolt with the internal keyboard unplugged.

Plus, the other person's suggestion to replace the keyboard.

Kinda risky, but you could also see if you can unsolder or cut the track to that specific broken key. There is the risk of completely borking the keyboard, though.

there's multiple ways to skin this cat, but in your shoes: i would use xmodmap to remap or disable those keys.

This is a helpful blogpost on disabling input devices in Wayland