I have read the whole Mueller report. It isn’t light reading, but you don’t have to be a lawyer to get through it. One point was that the grand jury concept was established by Article V of the Constitution and is not subject to presidential, congressional or court rulings for its authority.
The biggest revelation was that Mueller was working with tied hands in a way that was deliberately not made plain to the public. The only reason Mueller did not recommend charges against Donald Trump is that since a sitting president can’t be charged and tried, it is also illegal to recommend charges against him. There was plenty of evidence to charge Donald Trump with obstruction of justice, but it is simply not allowed against a sitting president.
It is obvious from reading the actual report that Attorney General William Barr’s summary of it was not merely misleading. It was an outright lie. The Mueller report specifically and carefully established the three necessary points for a case of obstruction of justice: obstructive conduct, corrupt intent and a ‘nexus’ to an investigation. The Mueller report has hundreds of footnotes and references to court cases and government procedures. It is airtight.
The Mueller report also listed page after page of incidents where Russia interfered with the election with the clear intent to help Trump win. It also listed multiple times where the Russians and the Trump campaign tried to coordinate but failed.