IMO, this would be a major advantage of countertop units. Buy two or four or six or eight, store them away in the cabinet when they’re not in use and enjoy the extra counterspace, bring them out when you need them.
It’s not THAT much of an advantage, since the area of unused burners can be already used as extra counter space, since it flat and resilient. Actually that seems like a major advantage over a gas stove, that’s rarely mentioned.
I thought about doing this, but it didn't make any sense for me. The countertop units are inefficient in terms of space compared to regular stovetops. This isn't suprising, due to component sharing, the need for a case, etc. As soon as you regularly use two of them, you might as well have a stovetop.
There are also down considerations of power (wiring and maximum output) and noise (induction units have fans, which are less noticeable in stovetops), safety (accident risk from cables, tilting, etc) and convenience.
It might work if your everyday usage involves zero to one units. Which is certainly possible, if you don't cook much, but even if you are and you're using other heat sources like a rice cooker, oven, grill, microwave, etc.
Not a terrible idea to have one around when you're limited by your normal capacity, or when you want to simmer a stew at a buffet, or your stovetop breaks or you are redoing your kitchen.