I know the Feds filed civil rights charges against the cops in the Rodney King incident, and were prepared to do the same in the George Floyd incident - many thought that this violated the Constitution's prohibition against double jeopardy, but the contrary view prevailed. But note - in each case, the Federal civil rights charges were targeting government employees who were alleged to have violated a person's civil rights under color of law. IANAL, but I don't see much of an opening for similar charges against Kyle - unless they just decide to proceed anyway with bogus charges based on the unspoken premise that "the process is the punishment." (The Feds were involved in the George Zimmerman case as investigators, but note, no federal charges were actually filed after Zimmerman's acquittal.)
As far as the yahoos outside the courthouse, the news report I saw said there were both "protestors" and "counter-protestors" out in front, but the newsies made no attempt to interview any or give an idea of the relative size of the two groups.
I still don't see that every person on a Kenosha jury will vote to convict Kyle of anything since even the prosecutor said the perps were involved in the rioting that destroyed a good part of their home town. But it only takes one person who either loves antifa/blm, hates guns, or is intimidated by the protestors to dig in their heels as a lone voice for conviction and hang the jury.