getting private key from keystore in PKCS8 format

so in my app i encrypt my data with AES key and encrypt that key with an RSA pair. i then save that pair to the KeyStore. when retrieving the private key from the KeyStore i need to format it to PKCS8 how ever i cannot format the private key because you cannot access private key encoded from key store. is there a way to generate the pair in PKCS8 format? or maybe a workaround in order to format the private key without accessing the encoded?

generating the keys:

    fun generateRSAKey(context: Context): KeyPair {
        val keyPairGenerator = KeyPairGenerator.getInstance(
            AppConst.RSA, "AndroidKeyStore"
        )
        val spec:AlgorithmParameterSpec
        if(Build.VERSION.SDK_INT>=Build.VERSION_CODES.M) {
             spec = KeyGenParameterSpec.Builder(
                    "privateKey",
                    KeyProperties.PURPOSE_SIGN  or KeyProperties.PURPOSE_VERIFY
                )
                 .setDigests(KeyProperties.DIGEST_SHA256, KeyProperties.DIGEST_SHA512)
                 .setKeySize(1024)
                .build()
        }
        else
        {
            val start: Calendar = Calendar.getInstance()
            val end: Calendar = Calendar.getInstance()
            end.add(Calendar.YEAR, 100)
             spec = KeyPairGeneratorSpec.Builder(context)
                .setAlias("privateKey")
                .setSubject(X500Principal("CN=Sample Name, O=Android Authority"))
                .setSerialNumber(BigInteger.ONE)
                .setStartDate(start.time)
                .setEndDate(end.time)
                .build()
        }
        keyPairGenerator.initialize(spec)
        return  keyPairGenerator.generateKeyPair()

    }

getting the keys:

val keyStore=EncryptionUtil.getKeyStoreInstance()
            keyStore.load(null)
            val entry: KeyStore.Entry = keyStore.getEntry("privateKey", null)
            val privateKey: PrivateKey = (entry as KeyStore.PrivateKeyEntry).privateKey
            val decryptedAES = EncryptionUtil.decryptRSA(
                android.util.Base64.decode(
                    aesKey,
                    android.util.Base64.DEFAULT
                ), KeyFactory.getInstance("RSA").generatePrivate(PKCS8EncodedKeySpec(privateKey.encoded))
            )