Jonah was in the belly of a big fish for 3 days before he made his way to Nineveh. Jesus was in the tomb for 3 days before He resurrected. This was the sign of Jonah Jesus told the Jews when they asked for a sign (see Matthew 12:38-40). Jesus also reminded them of Nineveh repenting at Jonah’s preaching.
When Jonah was in Nineveh, he preached that the city would be overthrown. Given his attitude towards the people of Nineveh, I doubt he performed miracles and he probably could not wait to leave. When the king of Nineveh heard what he said, surprisingly he did not issue any order to arrest, kill, or deport Jonah. Instead the king led the people to repent. In the end, God relented.
We see God’s grace in this matter. Instead of destroying Nineveh directly, He gave them a chance in sending Jonah. In contrast, God sent many prophets to Israel. Some, eg Elijah, even performed miracles, but the response was very disappointing.
We are no better than Nineveh or Israel, but God sent us Jesus, one greater than Jonah and the prophets. That shows His grace for us.