It's too bad the Android keystore doesn't support secp256k1 so it can't be used for Bitcoin wallets. A hardware wallet with dedicated display and input is much better but the keystore could at least protect the seed and require user presence for use. Curve25519 would be nice too.
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I’m proposing direct support of secp256k1 in the TrustZone for future phones, but unlikely in v1. What else would you like to see at the TrustZone level under Android?
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It would ideally be one of the curves provided by a StrongBox Keymaster implementation, which only mandates P-256 for now:
developer.android.com/about/versions
The Titan M on the Pixel 3 provides the first implementation of that, among other features it implements:
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For a phone aiming to implement solid cryptocurrency support, the best approach would pretty much be integrating a whole Trezor Model T into it with a dedicated touchscreen for display and input on the back of the phone. Having a protected input/output channel is important.