I recently finished my KSP2 For Science! playthrough by completing the last 2 missions: the game's final Big Boss mission, Under Pressure (10 kerbals to Eve and back); and The Crater Conundrum (Gilly).
Here are a few of the unique things I did for this mission:
One single launch rocket SSTO to LKO
11 kerbals to Eve and back versus the 10 required
All kerbals traveled in command pods or crew modules - no rumble seats
Launch to LKO
This is the heaviest