As well as the pitches Db G Bb E which you mention, there is also the C in the bass (I see you also notated that as "pedal point"). I agree with Richard that the key is temporarily f minor, and I'd argue that the chord is indeed V7♭9. Arguments in favour of this analysis: the chord precedes i, it has all the pitches of V, and it doesn't have any which mitigate against the impression that it is chord V. What's more, the C is in the bass, strengthening the impression that C is the chord's root. Analysing a chord as some classified chord over a separate pitch as pedal is what you have to resort to if the pedal note doesn't fit harmonically in with the chord; however, here, it does, so it sounds like part of the chord rather than a discordant pedal, so the above classification accords with what the chord sounds like.
Moreover, I'd say that this classification is not just credible but the only credible one: Richard's alternative, viio7, has dominant function; add to this the actual dominant in the bass, and the result is the aforementioned V7♭9.
As for Richard's argument that Haydn rarely uses true ninth chords, rare they might be, but why not classify a chord as such when the evidence for this classification is so strong?