Great! Apps like these are sorely needed. My feedback would be, apart from what others are saying about sub vs one-time purchase, to look at what Leechblock firefox extension is doing.

The key point is to make it harder (but not impossible) for me to use the phone. A "Do you need this?" is a great start, but since I can easily sneak by, I will soon do that. Even if I click "1 minute" to get a reminder, that should not be a simple notification, but back to the large big screen covering things.

What LB does is genius. You can enable a barrier so that if you reeeeeeally need to, you can get around, but it's annoying and time consuming, and thus the quick loop of "pick up phone and get stuck" is broken. The barrier in LB can be to type a (long) passphrase, or my favorite: a 64-char random string which cannot be copy-pasted. You need to manually look at 2-3 chars at a time and replicate the whole thing. Very effective.

But again, also the snap back to reality thing. If I keep using it, throw up a big overlay with a good question "Is your attention well spent?" for example. Make me wait before I can continue.