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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It only supports P-224 (secp224r1), P-256 (aka secp256r1 and prime256v1), P-384 (aka secp384r1) and P-521 (aka secp521r1). The StrongBox keystore strips that down to supporting P-256 since it's very minimalist by design and only the 128-bit security level is truly important.