It's unfortunate how there are not better birth control options available by now. Condoms are intrusive and make sex significantly less pleasurable for many people. The pill has a number of well documented side effects and many women anecdotally report a variety of other problems and reactions that make them unwilling to use it or other hormone based methods. IUDs are effective but also can have side effects for some women that in my experience are under reported / downplayed that make them not an option. All the other options I'm aware of have issues with effectiveness, side effects and practicality that make them not compelling options.

The temporary 'vasectomy' based on injecting a gel seems promising but needs more study and hasn't yet been approved in the US to my knowledge.

Given all this there's a reason natural methods like the rhythm method and withdrawal are still used despite lower than desirable effectiveness. People often talk like contraception is a solved problem when it's really not for many couples. Maybe this app is not as effective as would be desired but if it's improving on the unaided rhythm method it's still valuable.