Sorry, but this is wrong. One of the several charges, among others, that Michael Cohen was sent to prison for, campaign finance violation, had to do with the election. And of Course Roger Stone was indicted and convicted of lying about his involvement in obtaining Russian Hacked, DNC-Hillary emails, via Julian Asange as an intermediary, on behalf of the Trump 2016 campaign. Stone was convicted of perjury, but this of course is in no way dispositive of the thing he was lying about, i.e., collusion! The act Stone was lyhing about does not have to be called "collusion," you can substitute several synonyms, but the act itself is of course collusion all the same. Then there are the numerous indictments (at least 36!) that came from the Mueller investigation, and numerous convictions, or confessions of guilt, and sentences. These all had to do with Russian involvement in the 2016 Trump election campaign, or else illegal acts discovered incidental to Mueller's investigation.
In addition to Stones Perjury conviction which clearly was related to indirect collusion between the campaign and Russian operatives, there is now known one case of very direct collusion not yet prosecuted, and may never be, associated with the Trump campaign. This was identified by Mueller, and later the Senate investigation shed more light on this collusive effort involving the Trump campaign Chairman and his partner, a Russian intelligence agent. According to these investigations, the Campaign Chairman regularly shared private campaign polling and other campaign data and information with his partner and Russian Agent, Konstantin Kalimnik. This was simply a continuation of the close working relationship that Kalimnik and Manafort enjoyed when Kalimnik was acting as Manaforts right-hand-man in managing the election of the Russian plant, and former Ukrainian President, Viktor Yanukovych. They two used similar disinformation campaigns to get Trump elected, as had been successful with Yanukovych. (Yanukovych is now living in exile in Russia.)