It's not an app (although those apps may help implement it, idk). It's a method from a researcher B.J. Fogg, who wrote a book called "Tiny Habits" [1]. I haven't read that one, but I listened to a similar approach in "Atomic Habits" [2].
yes. I haven't read atomic habits but I also understand it is a similar approach.
Worth taking the free 5 day program via email on the tiny habits website.
The insight there is that you need less motivation to act if the action is very easy so you make it as easy as necessary so that you don't need much motivation.
[1]: https://tinyhabits.com/ [2]: https://jamesclear.com/atomic-habits