Currently, Storage uses localforage underneath to abstract away the various storage engines while still providing a simple API.
When running natively, Storage will prioritize using SQLite, as it’s one of the most stable and widely used file-based databases, and avoids some of the pitfalls of things like localstorage that the OS can decide to clear out in low disk-space situations.
When running in the web or as a Progressive Web App, Storage will attempt to use IndexedDB, WebSQL, and localstorage, in that order.