The new zcash shielded Ledger application is already compatible with the new stax/flex devices and available publicly for everyone.
You can read more about it here Unlocking Privacy: The New Zca...
Currently, this app communicates exclusively with the Zecwallet Lite Desktop Wallet. You can find more about this wallet here: GitHub - Zondax/zecwallet-lite: Zecwallet-Lite is z-Addr first lightwallet for Zcash.
To encourage broader adoption, we’ve published a comprehensive integration guide to help developers integrate this app with other wallets like Zashi, Zingo, and YWallet. Check out the guide here Zcash integration Guide
We provide 2 different types of integration packages to facilitate the integration: