Those temptingly cheap sensors aren't quite such a bargain if you have to buy IKEA's own $109 / £60 hub to make them work.

source https://www.techradar.com/home/smart-home/despite-being-designed-to-connect-and-just-work-it-turns-out-ikeas-new-smart-home-sensors-actually-have-some-specific-confusing-hub-requirements