If the app is public
The main CTA should go straight to the App Store to reduce friction. This route still helps as a stable footer and sitemap destination.
Download
Download Nippon or request access to the beta build.
The main CTA can always fall back to this page when the App Store link is not ready or when you want one lightweight page that explains release status.
If the app is in beta
Use TestFlight as the main CTA and add a short explanation that access may roll out in batches.