They can only make the public aware of what they learn (which Trump supporters will all dismiss as "fake news" ), and then recommend to the DoJ that the DoJ follows up.
The DoJ should already be hard at work on pursuing the top-level people behind 1/6, not waiting on Congress. The apparent inaction of the DoJ so far in this regard is what is most troubling, and nothing in your OP contradicts this concern.
Timing also matters. We're already at a point where the DoJ can't or won't do anything against the major 1/6 conspirators until after the November elections. As far as I'm concerned, that's practically game over for democracy in America right there. Indictments, prosecutions, and convictions only happening in the second half of Biden's term is too late to do enough good.