Barr's summary says, "In cataloging the President's actions, many of which took place in public view, the report identifies no actions that, in our judgment, constitute obstructive conduct, had a nexus to a pending or contemplated proceeding, and were done with corrupt intent …"
So yeah, tweets, jokes at rallies, offhand remarks, interviews (the Holt interview comes to mind), dissing Mueller's witch-hunt, all that and more is involved in the accusation that Trump obstructed justice.