How to find a practical part for a master thesis in IT (Blockchain)
You go around organisations and ask them about what they would be interested. Having a network is a huge benefit here.
You look into the introductions of the academic papers. See what real-life problems are recent articles talking about.


Basically those two. It does not need to be that good of an application, because it is even customary that the applications are stupid (simple) in academia. Real-life has all those legal issues like information security, confidentiality and such that you may not wish to be bothered with.

EDIT: Also real-life corporations are extremely unwilling to reveal their data, but also the intent of entering a market. An academic version is not even nearly ready business. I have seen applied math papers about how well the food and wine work together done for chemical corporation. You can guess that the end-project the theory was made for had only a little to do with wine and food.