I have something similar, but wifi. Never even tried to connect to it, because you just use the buttons to set temp & time.

I can imagine, though, that an app might have buttons for ‘eggs’, ‘yogurt’, ‘steak’, etc. Or maybe let you program temperature-time sequences. Or let you check how much time is left from the next room. Conveniences. Definitely no need for them to phone home, though, except maybe for an ad-driven ‘recipe of the week’ type thing.