I am fortunate enough to run a lifestyle business in this space. I market it as personal productivity software that lets you pick what to block and for how long, then prevents you from changing the settings until the time is reached.

It's freemium and only a one time payment for pro (ie - not investor friendly) but I really enjoy being able to work on improving it every day. I sometimes get nice emails from people which helps motivate me more.

My app is called Cold Turkey (https://getcoldturkey.com). It's for Windows and macOS only, because of the security restrictions on smart phones. It uses browser extensions (with native messaging) to do the blocking, but if you disable the extensions during a block, Cold Turkey closes your browsers until you re-enable them.