I can't speak to laptop keyboards that far back in time, but for a very long time, Thinkpads and Dell Latitudes had the best keyboards for laptops (obviously they weren't going to compare to a Model M or other mechanical keyboard).
But even these have gone away, to be replaced by the shitty island keys.
You could unplug it from the computer (it was a mini-din PS/2 style plug). The keyboard itself wasn't mechanical (not a buckling spring or similar system), but it did have full-travel keys and a nice feel for typing on.
I got mine used and had to build a custom battery pack from old cell phone batteries, which made me have to remove 2 meg of RAM (to fit the larger custom battery pack), leaving me with 6 meg instead of 8. I had Caldera OpenDOS installed on it:
http://www.deltasoft.com/opendos.htm
http://esca.atomki.hu/paradise/dos/opendos-en.html
https://en.wikipedia.org/wiki/DR-DOS
...with Monkey Linux installed on top of that (Monkey is a distro that used DOS for the underlying file system - you could even share data easily):
http://projectdevolve.tripod.com/ (downloads don't work)
http://www.ipt.ntnu.no/~knutb/linux486/download/monkey/monke...
I'm honestly not sure where or if you can still get a copy of that distro - I should look into it; maybe I should host my copy somewhere...