ED25519 Provider-Object Format not recognized?

[commel]

I am implementing a decoder for a ED25519 key with a custom oid and want to repackage this key with the genuine oid to forward it to the default provider.

Given the video about decoders and the man-pages about provider-objects, I need to repackage the key (where ed25519 has just its binary representation and no additional parameters) in OSSL_PARAMS. There where I am struggling.

This is my current implementation:

static int ed25519_pem_decode(void *ctx, OSSL_CORE_BIO *cin, int selection, OSSL_CALLBACK *data_cb, void *data_cbarg, OSSL_PASSPHRASE_CALLBACK *pw_cb, void *pw_cbarg) {
        ...

        OSSL_PARAM param_privkey[4];
        int param_type = OSSL_OBJECT_NAME;
        param_privkey[0] = OSSL_PARAM_construct_octet_string(OSSL_OBJECT_PARAM_DATA, &oct->data, oct->length);
        param_privkey[1] = OSSL_PARAM_construct_int(OSSL_OBJECT_PARAM_TYPE, &param_type);
        param_privkey[2] = OSSL_PARAM_construct_utf8_string(OSSL_OBJECT_PARAM_DATA_TYPE, "ED25519", 0);
        param_privkey[3] = OSSL_PARAM_construct_end();

       ...

        rc = data_cb(param_privkey, data_cbarg);

This results in the following outputs:

Could not find private key of key from example-priv.pem
80ABC4AC7B700000:error:1608010C:STORE routines:ossl_store_handle_load_result:unsupported:crypto/store/store_result.c:151:

I would be happy if someone could hint me into the right direction, why the default provider seems not to be able to read the key (after it has been read by my provider?).