Dismiss modal when completing a flow on Mobile

I am working on a mobile app and the flow is mainly to add one or n accounts. The flow has 3 steps and you can't jump to the next step if you haven't filled the previous one. When designing the flow I found that if I press the cross button by mistake i loose everything, so I added a confirmation modal to not loose our users. What do you think? is it something very common on mobile?

Thanks!