Hmm, that's possible. There clearly are spren much larger and more powerful than Syl, such as the sea spren in Axies the Collector's interlude, and that could actually be the point of that particular interlude....showing us a glimpse of these godlike spren that bond with the Heralds.
In fact, a few people have proposed that spren are splinters of the Almight's shard, much like Seons are thought to be the splinters of Aona's in Elantris...the problem with this theory has always been that spren and the Heralds and the Knights Radiant seem to be in existence while the Almighty is still alive, before Odium kills him....but is there anything to say that the Almighty couldn't have splintered his own power or shard long before his death? Not enough to leave him powerless, but definitely carving off slivers of his own Shard or power to share amongst the Heralds and Orders in the form of spren, segmenting his own divinity as it were. This could be what enables Odium to kill him in the first place...his power is too spread out, shared amongst his Heralds and throughout the world in the form of lesser spren to effectively fight back.
I'm thinking about how Brandon's confirmed that the Returned in Warbreaker are supposedly Splinters, but nothing in the book or elsewhere suggests there is another Shard on that world other than Endowment, who definitely seems to be alive still, at least as there's a voice that talks to the Returned before they are sent back. Who says Shardholders have to be dead for their Shards to be splintered? Maybe they can splinter their own voluntarily.
