They're not making a movie; the entire series is a prequel to the 2016 movie Rogue One.
In any case, i would be careful with such absolute statements
It is logical enough to conclude that a story ending in two intelligence agents flying off for a time-sensitive meeting with a confidential informant, is an immediate prequel to the story that begins with the same two intelligence agents landing and meeting that confidential informant.
This is not quite the same situation as the end of Rogue One and A New Hope, where some people make the argument that Rogue One ends just a few minutes before ANH begins; I am not convinced by that argument, although the cinematography certain seems to be leading us there.
The ending scene of RO is the data handoff and narrow escape of the Tantive IV with Leia, R2-D2, and C-3PO on it.
How is that not a direct continuity into the opening scene of A New Hope?
I think you might've fallen for some of the jokes about it being a prequel.
They really take their time filming this kinda stuff so don't hold your breath.
There indeed is absolutely no planned sequel to or continuation of Andor, nor currently any known plans for the creator of it to create anything else in this franchise. I'd sure like it if he did, though.
No. A masterpiece would not have any fluff. There are all number of scenes/characters that could be cut from Andor without any real impact. Entire scenes and characters could be dropped without impacting the narrative. (The entire forest planet sequence imho.)
Andor is a product of the "for your consideration" form of review made popular by the Academy (oscars). Each scene is excellent. Each scene is a cinematic tour de force. But they are all independent scenes. Rearrange the order, shuffle the scene deck, and little changes as the scenes are not dependent on each other. The overall narrative is thin. That may make for good/popular television but it is not deserving of "masterpiece".
I also think "masterpiece" is a heavy term to throw around but the emotional impact of the this series and the complexity of its narrative as it catalogs a hero's journey from reluctant participant to true believer with an epic story arc can be held up next to most film and historical epics like Laurence of Arabia, Ben Hur, The Matrix, the Original Star Wars trilogy, Dune, Kingdom of Heaven, Gladiator, The Handmaid's Tale (series), The Odyssey (epic poem). His personal journey which leads to his persecution and enslavement, his role in leading a slave uprising, rescuing his friends from the aftermath of a rebel uprising, building the foundations of a rebel army, risking his life countless times and ultimately sacrificing himself to prevent his enemy from having an insurmountable edge.
The series makes the very popular "Avengers" film series look like trite dogshit and does the same for most of the "Star Wars" sequels and prequels so I don't fault people for using the term "masterpiece".
Was your gripe about superfluous scenes, where you mentioned the forest planet, a reference to the first few episodes of season 2? That forest plant is Yavin IV, the plant where the rebels eventually build their first base, and those rebels are some of the first recruits to the rebel army. I believe those scenes were intended to show how the rebellion lacked leadership and how Andor and others had to step up to provide that leadership.
I would say that there is not a single scene that can be removed from these movies without negatively impacting the story/theme/narrative.
Some say that Star Wars IV and V fit this definition but I would say there is some eyecandy fluff that could be cut.
Appropriating Saint Exupéryian (et al.) notions regarding the unattainable (perfection) to judge an artwork is a sucker's bet to me.
And in the cited works I rate as cinematic masterpieces scene editing (e. g. removal) is most certainly possible without having a negative impact on your criteria, but that is a completely moot point anyways.
With regards to Andor's forest arc: It is, amongst other things that are most certainly more appreciated by a specific set of people, a very interesting mediation on time and the notion "where there's competence, there's always also incompetence", often manifesting in very comical and surreal ways.