Tiny robots climb walls carrying more than 100 times their weight
newscientist.com
newscientist.com
Another related video with Geckos and synthetic 'geckskin':
Yes, a 12 gram robot can carry 2,400 grams of weight but this does not necessarily mean you can build a 12 kg robot that will carry 2,400 kg up the side of a building because it would require drastically more stickiness/surface area friction.
I think this is what you meant by "Square-cube law."
Though I could be wrong.
Tiny roombas to help find the pen you just sat down, turned your head, turned back, and the pen is gone. You know it went somewhere, but you're not quite sure where; it might not even be in the room anymore.
Tiny roombas to clean your bathroom, or unclog pipes, or micro-repair infrastructure like houses and roads. Tiny roombas to help to agriculture work, or terraform Mars.
Giant roombas to terraform Mars, the size of houses.
sigh.
On a larger scale, "pigs" [1] are used to clean and maintain oil pipelines.
Tiny Roomba, like the robot in OA, won't require power to stay stuck to window.
Tiny Roomba, like Roomba's today, will know it's power reserves and be able to return to charging station before shutdown.
Tiny Roomba will be solar powered.