Any ideas on the hero from West Blue? Is it even important enough to try and guess?
Maybe this "Hero" was the one that showed him the Cherry Blossoms that "allegedly" made him feel better. Hirurluk was also from the West Blue.
Maybe this "Hero" helped alot of legendary figures. The famous Whitebeard and Roger Scene comes to mind, both sitting under Sakura Trees. We know at least that Roger was also terminally ill at this point, since he told Whitbeard that he was going to die.

As of Whitebeard, it is unclear if he had some health declines here, but they could have found the same solution for their health, which Dr. Hiruluk found. But big chances everything I wrote here is garbage. I am sure some of the timelines won't fit. I was just too lazy to check.

I kinda hoped to see Dr. Kureha during this flashback, given her current age she lived through so many events in One Piece, it is crazy. We still know nothing about her past and she mentioned the D. at the End of Drum Island. Dr Hiruluk could also be a possibility, since he's also still alive somewhere. We might be seeing him in his Thief role if Oda goes in chronological order. But, then again, we might not see any of them.