Conditional callback with deno_kv_oauth

Hello I am using deno_kv_oauth for my application and am trying to do the following:

I want users to a have an internal uid that is the same format between oauth providers.

Here is the logic flow I want to create:

User signs in via oauth ->
Redirected to callback page ->
if an existing user -> redirect to homepage
if not an existing user -> create a new internal user KV / id <- problem!

I can't seem to find a way to figure out how to return a different redirect and save the cookies.

(also I am using Hono but I do not think that is the problem?)