What's the current state of web apps on IOS? Does Safari yet support local databases well enough to build useful web apps?
Pretty much every app I can think of building for my family could just be a website iff local browser-resident persistent data was a thing. (And in some cases I wouldn't even need that if they were going to be always-online.)
I used dexie js from dexie.org to persist indexedDB, vendoring the script in a sidecar js file or inlining it - good for your iOS persistent local db, android too.
I could also recommend SQLite with OPFS, if you’re comfortable with adding a web worker. I personally find it a lot easier to reason about than IndexedDB (even with a wrapper, it’s still a bit tricky to work with, and you get the power of SQL with SQLite).