I was trying to get a keycap for m0110a, but there was a Mitsumi version and an Alps version of the keyboard switch.
Can I buy Keycap regardless of the version?
At a glance, it looks compatible
They aren't *strictly* compatible but you can get 'em on. Just be mindful cause there are both beige and platinum colorways and they can be hard to distinguish now that everything's yellowed with age. Beige has significantly darker keycaps and platinum keycaps won't match. You might have issues with the Return keycap if you use it with a different type of switch to the one that the keyboard came with.