I have never considered meeting 2.Nc3 with ...f5. Isn't White better if he simply recaptures on e4 in your line?

One very annoying line I faced years ago is 1.d4 d6 2.Nf3 f5 3.Nc3!? Maybe Black is OK there theoretically (I have no idea really), but the Pirc/Leningrad player can eliminate it with 1.d4 d6 2.Nf3 g6(!), waiting for 3.c4 or 3.g3 (or 3.c3 or 3.b3 or 3.Bf4...) before committing to 3...f5. This depends on 3.e4 Nf6 working out to a normal Pirc, and I think it does, though you lose some options against White lines with Bd3 and/or Nd2.

I would pay special attention to lines within the Leningrad where Black is often advised to switch to a Stonewall setup with ...d7-d5 (i.e. some b4 lines, early b3 lines, c3 lines etc.), if you have any of those in your repertoire. Obviously you would lose a tempo if you did this after 1...d6. Though in my experience it's extremely rare to face a White player who is sophisticated enough to try to punish the lack of flexibility in Black's move order in this way.

Btw. the Yrjölä/Tella book gives some interesting lines against 1.d4 d6 2.Bg5, recommending chasing the bishop with 2...h6 3.Bh4 g5.