This is one of the more complicated speculations
Maybe he got in contact with Dragon through Vegapunk considering the latter was looking for good marines. Someone warned the Revos about the assault on Baltigo afterall. On the other hand someone also informed Cp0 about Baltigo's location, though I doubt this person is Aokiji. The gorosei were straight forward regarding his position, and considering Cp0 is their personal force then doubt it's Kuzan. Revos too sounds wacky at this point.
He's also not in contact with Sakazuki as he had to personally tell Smoker about Doffy, meaning he's not in touch with HQ anymore.
Definitely not Sword working on his own accord, he knows the value of his strength and wouldn't sacrifice the position to spy on Bb.
His convo with Smoker showed he's still the same man he once was.
Now that he left the WG, his perspective naturally changes drastically. As an admiral he had some sense of justice but that has always been limited by his position, but now that he's free he could expand on his world views, mainly contemplating on Ohara as that's where Kuzan's mindset first changed, going from "fired up" justice to "lazy justice", and that's also the only established lore for his character lol
For the moment he's hitchhiking with Teach as means to stay active and learn more about the lawless world, ultimately his goal could be redeeming his actions in Ohara and uncovering the void century, so Raftel is the safest answer for that.
At some point he will leave the crew but no idea where he goes from there, he might very well end up dying.