@achow101 noted we don't reject them therefore they must be silently accepted. This is not part of the specs, we should remove them. Also cc @sipa.

I can take care of this.
size_t GetSize() const override { return m_pubkey.size(); }
    std::string ToString(StringType type) const override { return m_xonly ? HexStr(m_pubkey).substr(2) : HexStr(m_pubkey); }
    bool ToPrivateString(const SigningProvider& arg, std::string& ret) const override
    {
        CKey key;
        if (m_xonly) {
            for (const auto& keyid : XOnlyPubKey(m_pubkey).GetKeyIDs()) {
                arg.GetKey(keyid, key);
                if (key.IsValid()) break;
            }
        } else {
            arg.GetKey(m_pubkey.GetID(), key);
        }
        if (!key.IsValid()) return false;
        ret = EncodeSecret(key);
        return true;
    }
    bool ToNormalizedString(const SigningProvider& arg, std::string& ret, const DescriptorCache* cache) const override
    {
        ret = ToString(StringType::PUBLIC);
        return true;
    }
    bool GetPrivKey(int pos, const SigningProvider& arg, CKey& key) const override
    {
        return arg.GetKey(m_pubkey.GetID(), key);
    }
};
enum class DeriveType {