True. We don't have much information on the Almighty's Shard, but Cultivation also seems like a good candidate. Perhaps the Almighty created the planet itself, Cultivation gave it live, and Vorinism, not knowing any better, attributed the whole process to the Almighty himself.
As for the spren, many of them seem to just be part of the ambient magic on Roshar, as has been mentioned before. However, two types of spren we've seen thus far - honorspren and the as-of-yet unnamed "symbolheads" (if they really are spren) - are different from the others; they are sentient, capable of communication, and are directly involved with two types of magic on Roshar: Surgebinding and Soulcasting, respectively. If any spren is a good candidate for being related to a shard, it's those two, not the more common varieties like rainspren or gloryspren.