Update: In the console I get an error that looks like this: Failed to return view entry from archive for view model with tag jindo-compactTrailing with error: SwiftUI.AnyCodable<SwiftUI.(unknown context at $1d30c3df8).SafelyCodableRequirement>.(unknown context at $1d30caf74).Errors.noType(mangledName: "7SwiftUI18TimeDataFormattingO10ResolvableVy_AA0cD6SourceVAAE15DurationStorageOys0H0V_G23[...]27CompactCountdownFormatStyleVG") Which I believe either suggests there's some internal requirement my formatter doesn't know about or SwiftUI checks that formatters are of a specific type.

Great questions: Do you need to worry about bandwidth costs? Not particularly. It's an initial download + syncing for any updates for a set amount of time (say 4ish months). Few large assets. Are you obliged to pay the provider of the content even for unauthorised downloads? Nope, it's content I'll be making and updating myself Is the type of content, or the main market for your app, something that is often pirated? I don't believe so no, the information itself is generally all already publicly available. I'd just be doing extensive amounts of curation and data clean up to present the content in new/fun ways