It's more for sporadic use in games, with TVs and such, when having a full-size keyboard is inconvenient. Presumably it could also be used with a tablet, but more typically it's a small on-desk keyboard, perhaps foldable.

I was thinking of buying something like this a bunch of years ago, when I was looking into sorta-ergonomic devices to diversify my time spent inputting stuff.

Some of these micro-keyboards have a touchpad, and on the ‘gamepad’ keyboard it's apparently on the back.