It does indeed look similar.
Episode VI: Return of the Jedi would also arguably the most "easy" part of the SW Universe to adapt into KH as it arguably takes place on only two main planets, Tatooine in the Prologue to rescue Han from Jabba the Hutt and then the Endor forest moon where the final battle between the Rebel Alliance and the Empire takes place, the culmination of both the Prequel Trilogy and Episodes IV and V.
Most of the other action takes place almost solely in space with the exception of a small detour to Dagobah where Luke witnesses Yoda passing away.
The space battle of Endor with dozens of Rebel Mon Calamari Cruisers and Imperial Star Destroyers duking it out between hundreds of fighters flying between them would also be ideal for a Gummi ship sequence, the Battle of Endor being the biggest battle of the original trilogy and scale probably topped only by the Battle of Coruscant in Episode III between the Republic and Confederacy.
On the surface of Endor itself fighting the Imperials you could have Han Solo and Princess Leia as guest party members, possibly Chewbacca as well.
There would of course be also the opportunity for Darth Sidious/Emperor Palpatine as a world boss, possibly with Luke and/or Vader as guest party members, beforehand there could of course also be a duel against Vader together with Luke.
Due to the sheer vastness of the SW Universe including its own vast lore I was always skeptical about it being included in KH, but if it is a small "window only" experience possibly related to the Quadratum-side of the multiverse it might work.