Decentralized applications are theoritcal in life practices, the only utility in practice is web3, the real life aspect is not working. Nigeria isn't the only country that has substandard goods and they don't used Dapps to track fake goods. Some of the fake medicine and imported items that are sold in other countries down to Nigeria and their government isn't fighting it using Dapps.
There are other countries that have a traditional system that has reduced substandard goods and the Nigerian government can do it too just that the government will likely reject the idea because the system is corrupt, the people at the top all got rich through the corrupt system of substandard goods.
DApps are not just theoretical, with the advancement of tech a lot of things has been proven to be possible... Take for example who would have thought that you can generate a realistic video with faces and physics and even voice without using a camera to film someone... But A.I made it so possible that it is becoming hard to differentiate between A.I and real videos... There is still a lot of room for growth and dApps is not left out... It can be very practical the only problem is the adoption especially with governmental bodies