Venice's government failed to maintain itself in the face of an aggressive and revolutionary France, and yet I do not think that armed resistance would have been entirely futile. The mainland was lost, as had happened during the war of Cambrai, but I suspect that had the city not admitted French troops that it may have avoided being occupied and may instead have become a client republic like the Swiss. In 1848, after all, Venice withstood a lengthy siege by the Austrians; if the French were not directly admitted into the Lagoon, then IMO Napoleon might instead prefer a client state to delaying his continued offensives, and the Municipal government might survive as a third republic or part of the Cispadane Republic. Would this be plausible or was Campo Formio locked in by this point?