This would allow wallet operations like funding transactions with smart contract-based inputs such as LN, or any input the Core wallet doesn't know how to sign for.

https://github.com/bitcoin/bitcoin/pull/17211#issuecomment-933674310
}
    
    int nHashType = ParseSighashString(request.params[2]);
    
    bool sign = request.params[1].isNull() ? true : request.params[1].get_bool();
    bool bip32derivs = request.params[3].isNull() ? true : request.params[3].get_bool();
    bool finalize = request.params[4].isNull() ? true : request.params[4].get_bool();
    bool complete = true;
    if (sign) EnsureWalletIsUnlocked(*pwallet);
    const TransactionError err{wallet.FillPSBT(psbtx, complete, nHashType, sign, bip32derivs, nullptr, finalize)};
    if (err != TransactionError::OK) {
        throw JSONRPCTransactionError(err);
    }
    UniValue result(UniValue::VOBJ);
    CDataStream ssTx(SER_NETWORK, PROTOCOL_VERSION);
    ssTx << psbtx;
    result.pushKV("psbt", EncodeBase64(ssTx.str()));
    result.pushKV("complete", complete);
    return result;
},
    };
}
RPCHelpMan walletcreatefundedpsbt()
{
    return RPCHelpMan{"walletcreatefundedpsbt",
                "\nCreates and funds a transaction in the Partially Signed Transaction format.\n"
                "Implements the Creator and Updater roles.\n"
                "All existing inputs must either have their previous output transaction be in the wallet\n"
                "or be in the UTXO set. Solving data must be provided for non-wallet inputs.\n",
                {