The most widely used currently decentralized app / Dapp is a crpto-wallet.
Unfortunately due to the need to access the node of blockchains wallet Dapp become increasingly centralized. Users access their wallets through few commercial wallet providers.
Lots of answers posted are written without technical understanding of what a Dapp really is and quote marketing hype (crap) about what the marketers wish a Dapp could be doing.
To find what a Dapp really is please check this article -
What a Dapp really is
To find of the types of crypto wallets please check this article -
What do I need to know before creating a blockchain wallet