Update 29 Jan: If you want to play with this, use prerelease 5, not the latest prerelease 6. Here’s how to get prerelease 5, which has Apps V2 features:
curl -L https://fly.io/install.sh | sh -s 0.0.451-pre-5
Prerelease 6 is good if you want to test out the new Rails Dockerfile generator: Cut over to Rails Dockerfile Generator on Sunday 29 Jan 2023