They were hints.. but kinda disappointing that it was casual revealed in SBS.
Oda's just teasing shit. We'll get Franky + Scien lore in Wano Act 4.
The fact that Franky's Dad is marooned on the island Pluton is located on is like some Pin the Tail on the Donkey shit, honestly.
Kaido literally announced he and Linlin were going after the Ancient Weapons, Kaido wanted to activate Pluton, but didn't know how.
Crazy to think that for 26 years Queen was attacking Wano over Pluton, while Franky was protecting Pluton's blueprints from the WG. Both also end up dealing with Cipher Pol in indirect ways, as well.
Since Chopper and Queen have an extended history, too, I think Queen, not Vegapunk, will be the one to help stop the SMILE Fruits.
Since Kaido was working with Caesar, and Caesar and Queen already knew each other, it's very likely Queen was involved in SMILE production, especially since the SMILE Fruits were a "plague" to the people of Ebisu Town.
Scien will help Franky with laser tech in Act 4, and also help Chopper make a "plague" that reverses the SMILE Fruits. Queen was seen as smitten with Komurasaki in Wano; if Hiyori asks Queen to help save Toko, I think he'd consider it just because he's such a simp.
It's like with Bon Kurei: did Bon-chan do some seriously fucked up shit in Alabasta? Yeah. But, he's just so much fun as a character, that he was inevitably going to become an ally. Queen is too "fun" for Oda to keep him as a villain.