Unless Rainbow 2 and Sunstone play important roles in the next 3 episodes, AVSE was very much filler.
Also,> Aquamarine / Eyeball conclusion
You say that as if they needed a conclusive episode, and that episode wasn't conclusive at all. They're still out there, and maybe they'll cause trouble in these final episodes. However if they don't, then that episode was pretty pointless as well.
Sendoff is also a strong word for a lot of these episodes. Why So Blue only introduces more problems for Lapis rather than solving any of her lingering ones, and the same happened with Pearl in Volleyball. Jasper has way too many untouched problems for Fragments to be called a sendoff, Garnet and Bismuth barely featured in their so called sendoff episodes, and with In Dreams only featuring Peridot and Steven, it feels less like a celebration of Peridot's character and all the relationships she developed, and more like a quota fulfillment of "have an episode that involves Peridot."
Mind you that doesn't make them filler, because they're gonna be used as building blocks for the featured gems saving Steven in the end, but they aren't filler because of the reasons you listed.