Mine is the Affinity suite of image manip software. I don’t use it often, but I do use it often enough that I maintain a Windows box to be able to do so. That and I play a few games occasionally (at this point pretty rarely) that just work better/at all under Windows rather than Linux. Like 90% of what I do with my computers is great under Linux, but those last few elements make me not want to dump Windows entirely.
Honestly, a minimum viable product is entirely what Pokemon Go was designed to be. It exists to extract behavioral surplus from users and convert it into valuable action by inviting users to go to certain places in a community through placement of Pokestops and Gyms. Basically a tool to drive foot traffic, which Niantic can (and does) sell to businesses that want to drive that foot traffic. It worked brilliantly for years and still is a somewhat effective method of driving advertising and sales for real world businesses.