The ending of Kaguya-sama Season 2 in the manga is approximately at chapter XX. Keep in mind that there could be some minor differences in the adaptation process, but the main story beats should align.
Kaguya-sama's third season ended at a point in the manga that's a bit tricky to define exactly. It roughly corresponds to a particular storyline, but for the exact chapter, you'd have to do some digging on manga-related communities or resources.
The Kaguya-sama manga is indeed finished. It ended after a successful run, leaving fans with memories of an engaging and enjoyable story. The final chapters tied up loose ends and delivered a conclusive ending.
Yes. The Kaguya-sama manga has reached its conclusion. It provided a satisfying ending for fans. The creator wrapped up the plotlines and characters' arcs neatly.