This sounds great in theory. There was an app called sweatcoin which made it to the #1 app in the google plat store. There were SO many problem with the app. If there was a way to ensure people can't cheat, then maybe that would be something.
I've heard something about it as well, but haven't followed it later on. But it is to mention, that it's available in the US, UK and Ireland only..
I will describe the problem about SweatCoin shortly.They are using an algorithm, so that no one can cheat. To prevent cheating only 65% of the steps are verified on average. A lot of steps are just thrown away which makes it really difficult. Furthermore, this isn't the best idea to prevent someone from cheating.. and unfortunately, there is much room to cheat.
In addition, Sweatcoin keeps a small percentage of the steps in order to finance itself. So you pay practically the mediation of the premiums with your steps. Whole system is not really transparent...