This is related to #14150 and possibly others, but it's actually a separate issue.

For instance, when using the following query:
`bitcoin-cli scantxoutset start '[{"desc":"wpkh(xpubABCDEF/0/*)", "range":100}]'`
I can get a list of UTXOs, but no way to get back the index which derived that particular UTXO. So it's not much better than deriving on the user side and specifying addresses one by one, so that I already have a cache of addresses to match.

Not sure what the solution looks like. One way is to repeat the full descriptor in the utxo. That might get verbose though.
{
    const std::function<CScript(const CScript&)> m_convert_fn;
    const std::string m_fn_name;
    std::unique_ptr<Descriptor> m_descriptor;
public:
    ConvertorDescriptor(std::unique_ptr<Descriptor> descriptor, const std::function<CScript(const CScript&)>& fn, const std::string& name) : m_convert_fn(fn), m_fn_name(name), m_descriptor(std::move(descriptor)) {}
    bool IsRange() const override { return m_descriptor->IsRange(); }
    bool IsSolvable() const override { return m_descriptor->IsSolvable(); }
    std::string ToString() const override { return m_fn_name + "(" + m_descriptor->ToString() + ")"; }
    bool ToPrivateString(const SigningProvider& arg, std::string& out) const override
    {
        std::string ret;
        if (!m_descriptor->ToPrivateString(arg, ret)) return false;
        out = m_fn_name + "(" + std::move(ret) + ")";
        return true;
    }
    bool Expand(int pos, const SigningProvider& arg, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const override