Not sure if this comparison has been made yet (I haven't seen it, personally), but my husband came up with an interesting theory regarding Type: Null and Zygarde.
Type: Null is clearly based on a chimera, likely pieced together from different Pokémon...somehow. Perhaps it was created using other Pokémon's DNA, or cellsy'know, like those Zygarde Cells scattered across Alola. What if Zygarde Cells were used as a base for Type: Null? It does have a very similar body to Zygarde's 10% form... And not only that, but its animations are nearly identical to (but slower than) Zygarde 10%'s animations! It's also genderless (so much for it being the rumored multi-type breeding cat Pokémon), like Zygarde. And what are those green hexagons on its helmet...? Hm...! What does it mean? I don't know! But it's certainly interesting...
Type: Null helmet is Arceus's Cross, but in a smaller/more helmety shape. The point of alchemy is to achieve the power of Azoth aka God aka Arceus. But the hexagons and being made from Zygrade Cell's is definitely possible.
There is so much to this Pokemon it's insane.