And Mueller’s investigation covers the transition, so he already has grounds to interview Nunes

or on the commute to or from congress. however, there is an exception for treason and felonies.

so no problem indicting and arresting him on any charge mueller in practice would bring. i think we're way beyond misdemeanors here.

spinning false narratives to the press is no obstruction in and of itself, imho.
spinning false narratives to federal investigators *is* obstruction, and conspiring with the white house for the same purpose would also be obstruction, or conspiracy to commit obstruction.

subpoena to interview seems almost always in such cases to be a good idea. on the fairness side, you're giving the interviewee an opportunity to clarify or explain actions which may make seemingly criminal activity more excusable; on the prosecutorial side, your giving them an opportunity to confess or perjure themselves or implicate others.

So far, no answers.

Nunes is very publicly part of the obstruction conspiracy. Most likely he is also the recipient of tons of NRA Roubles. These things will turn out to be major errors.