The Beast and BM Pirates have been active for decades, so nothing new on them for the Gorosei. Also we could rule out the zoans Chopper, Onimaru, Drake, Orochi and Marco, as they dont have much besides the animal power. We can also rule Brook fruit out as It has been missing for a long time. Kin and Raizo could also be rules out as probably the WG dont even know who they are, and the fruits are more gag powers. Kanjuro fruit came from outside Wano, but cant see how the WG would have knowloge on Kanjuro and would seems kind random.
From the supernovas the Ope Ope is the only one with more deep meaning for the WG, but we already know about it, and from what Doffy say seems like it main power(Eternal Life Surgery) dont need awakening to be used.
That let us with Tama, Luffy and Robin fruits.
Robin is a prime target for the WG, and they were talking about her.
Tama power could somehow be linked to Zunesha.
But Luffy one seems the most likely. The WG had the fruit, Shanks stole the fruit from them, Oda already has given some more hints on the fruit in WsW vs Jinbei, and the gorosei seems to be talking about killing WsW because he probably knows to much while everyone is paying attention to the Emperors.
The thing that make being Gomu a shit is that the WG is seeing the guy with a D. name, with CoC, that have the only character that can read poneglyphs under him, that have connections with a lot of other D.'s, that have attacked the WG in various ways, that have the StawHat and have the superpower DF and they arent sending theirs full forces to destroy this guy who clearly is the New Joy Boy??? Makes no sense, but as its just a shonen could happen