Is there a companion app for Haiku?
We haven't yet created a "mirror" app, though one simple option for now would be to load the "share page" on your device (the one you get from publishing), then Publish in Haiku > Refresh on your device each time you want to see the change.
Can I preview my animation on a mobile device?
If you're planning to export to Lottie for use on mobile, we recommend installing the Lottie app from the App Store or Play Store. You can use editor.lottiefiles.com to upload your JSON, then it will give you a QR code that you can load with the Lottie iOS/Android app for previewing on your device.
If you're not planning to use Lottie and are developing a mobile web app instead (e.g. React/Angular/Vue) you can open your publish link directly in your phone; Haiku projects aren't "prototypes" per se, since they're production-ready. That is, what you see is what you'll get in the mobile browser.