In the Dune universe, Spice is organic in origin. It is extracted from the ground on Arrakis and therefore there is no direct contact between the humans and the sandworms involved in attaining the Spice.
While the worms are incapable of intentionally giving the spice to the humans, I think spice mining can be hardly qualified as exploitation. I also think that the process is ethical given that humans are not harming the worms in any way in the process of spice extraction.
With this in mind, could vegans consume Spice? Would it align with the vegan way?