I think the [modified] KDF example may be too new for most users of OpenSSL. For example, it appears OSSL_PARAM is part of an upcoming release: https://www.openssl.org/docs/manmaster/man3/OSSL_PARAM.html .
I think the new example is going to cause confusion for most users rather than helping them. Also, answers on Stack Overflow a pointing back to the wiki and the old example.
Perhaps you can add the new example as a distinct second example, and clearly state it is part of the OpenSSL 3.0 API.