At the end of The Mandalorian and Grogu, the Dragonsnake devours the Hutt Twins, the New Republic destroys their palace, Rotta joins the New Republic, and Din teaches Grogu to fly the Razor Crest. Everything that follows contains spoilers, and the interpretation is my own reading, so please treat it as opinion.
What does it mean? In my opinion, the Twins dying to their own creature gives the Hutt thread a clean close, since the same Dragonsnake they used to poison Din is what removes them. Because the film sits directly after Return of the Jedi in chronological order, and Rotta is Jabba's son, I read the Hutt storyline as a deliberate echo of that earlier film's criminal world, now being dismantled by the New Republic. That is interpretation, not something the filmmakers have stated.
Rotta is the more interesting case. He begins on Shakari as a gladiator who refuses rescue. Din beats him in the arena and spares his life, and that mercy is the hinge: Rotta later tells Din that Lord Janu and Commander Coin are the same man, and he finishes by choosing a side. It could be argued this is the film's quietest argument about what the New Republic offers people compared with the criminal families it replaces.
The Colonel Ward sequence matters for the same reason. The New Republic arrives and flattens the palace, which shows the faction acting with force, not only as the employer Din and Grogu work for. Set beside The Force Awakens, the next film in chronological order, that early show of strength gives viewers something to weigh. I am not claiming the film plans that connection, only that it is a fair question to ask.
The final image is small on purpose. Din and Grogu fly off together, and teaching Grogu to pilot the ship shifts the partnership from carrier and passenger toward two pilots, which, perhaps, is the most accurate summary of where the pair have arrived by this point in the chronology.
As a spinoff, it closes its own story much as Rogue One and Solo are also spinoffs that stand as complete stories. In my view, that makes this ending a finish more than a launch pad. The source I could read describes no larger sequel setup, and the film leaves Lord Janu's fate after the compound raid unstated, which I would read as a loose end rather than a setup.