Not an IPhone user: but honesty I'd rather have things open an actual browser tab, as then I can interact with it via all my standard extensions (e.g. adblockers), rather than be opened in a webview.
Also, given how often you need to change phones (given build quality), if I have important data and you're a web app, I rather the server be the source of truth, and the phone a cache (so I don't loose data when the phone breaks).
Also, given how often you need to change phones (given build quality), if I have important data and you're a web app, I rather the server be the source of truth, and the phone a cache (so I don't loose data when the phone breaks).