I've seen interest bearing crypto accounts. You can get 6% APY on stablecoins. Any project that promises you more than that is calculating APY for the current day or hour. 40% APY for less than a single day is just misleading advertisement.

Although I am generally against cryptocurrencies, I cannot be against the idea of building a decentralized banking system (cryptocurrencies are merely cash). I mean, if we get to do it with fiat, they surely deserve to do it with their cryptocurrencies.

Currently the smart contract software projects are focused on decentralized finance since the only input necessary for that is ETH currency. New tokens, decentralized exchanges and so on.

People created Chainlink to bring real world data inputs to Ethereum software. Data such as "package has arrived to its destination". It hasn't delivered on its promise yet unfortunately. If it ever does, all bets will be off.

I have multiple decentralized websites and even a search engine on IPFS (the p2p web3 protocol)