Wondering if I can add parameters to a Vercel deploy hook (specifically looking to overwrite environment variables)
if not this would be a great feature.
Hi, and welcome to the Vercel Community, @prestonbourne!
Deploy hooks are designed to be simple, unique URLs that trigger a deployment when called. As far as I can see, there are no parameters to the deploy hook.
However, I’d love to understand your use case so I can share it internally! 
Have you had a look at the Vercel API? It may be a better approach, especially when you need to manipulate environment variables or other deployment settings programmatically.