Don't pick nasus unless you know the enemy top and can reliably stack. <100 nasus games, don't even think about picking him into an uncomfortable matchup in ranked. Save the learning and experimentation for normals. Nasus is incredibly punishing if you fall behind in lane because his kit is very binary and he has very little outplay potential. If you're winning, it's by rolling people with your stats. If you're behind, don't even bother. You won't be fed enough to duel or one shot.
Across all my accounts I'm maybe at ~1k nasus games norm and ranked combined and I STILL would not willingly pick nasus into a few matchups. Gnar is a good example of a matchup I dodge. Vayne and Twitch are also instadodges, more vayne but the point stands.
The doge is really strong, but you always need to have a game plan with him and understand your role on the team. Dont be a potato nasus that rush sheen item and isn't remotely tanky for mid game.