Kinda reminds me of a degaussing loop from a crt monitor. Connects to the main board and just loops around the housing.

What's that about?

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Depends on what it is.
Could be an antenna.
Could be for radio interference compliance. Or a number of other things.

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Google the keyboards Make and Model for the schematic diagram. Parts layout and parts list.
Hopefully. You can get a download or something. That coil should be labled on the schematic and/or mentioned in the parts lay out or parts list.
That should give you a clue to it's function.

As a side note. That coil could be for a FCC compliance for a quiet RF environment for the computer itself and surrounding devices.
Look for a tag on the keyboard stating what FCC regulation the keyboard fulfills.
But. Yeah. Sure reminds one of a degaussing coil on a CRT. Also a AM home antenna.
I did my share of replacing CRT's in my day.
That would be cool hooking that coil up to an AM radio. See how it performs.

Too late to check any of that.
Whoops ¯\_ (ツ)_/¯

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Here to learn more so I can recycle more
My grades are my own opinion and not an official grade from Boardsort

My best guess is compliance

2nd guess an early wireless keyboard.
Some like Microsoft had massive antennas.
That often were out of compliance lol

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If curiosity "killed the cat." Wait! I better stop there.
After doing some further research on your question. Yes. I have the time to do this. I am retired. Of all the employment I had through the years in the electronic field. I never did home computers or main frame. So. I would like to know also.
LOL. ( After quite some time surfing the internet). The answer is right in your posted photo. Though part numbers on the plastic case and circuit boards are blurry.
One can see the battery case. The wiring reveals the answer. The battery powers the PCB. The PCB then is the low frequency transmitter. It's output feeds the coil which your question is about. All the right components are on PCB to be a primitive but effective transmitter. That keyboard most likely is early first run wireless keyboard engineering to satisfy customer demand. Wireless quickly evolved beyond that.
I totally 100% agree with lostinlodos. The 2nd guess.
It is an antenna for the wireless. Batteries drained quickly with that setup.
I got to hand it to the original owner of the keyboard. The battery holder doesn't show corrosion. So many individuals leave batteries in fine old antique equipment. Ruining them. Example. Old pocket transistor radios.
Ok. Enough said.

Interesting.


Another discovery I made while processing several keyboards...a lot of the wired ones cables, are steel wire. Figured it out by accident.

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Here to learn more so I can recycle more
My grades are my own opinion and not an official grade from Boardsort

Later designs incorporated the antenna into the keyboard traces.
You will see long copper traces through the keyboard. Not connected to the keyboard matrix. Sometimes the antenna is on another PCB.
It was all a of matter of eliminating those antenna loops and solid antenna wires.
That has little to do with tear down e-scrap.
But. You did ask. What is this?
Electronic manufacturing moves so fast. The cell phone you bought today is outdated already. Personally. Reminds of the electronic handheld calculators in the 70's and on.
Always a better and cheaper design.
What an industry. Glad I got into it. This might be a bit of overkill on your question.
But. Knowledge is power.