@jgleason You are correct, there is currently no way to cache tokens in Actions, you will need to use Rules for now to do what you are looking for.
This is a common ask from the community. There is a feedback post (although not limited to token caching in just Auth0 Actions) that seems to fit your needs. You can vote on the post and let Auth0 know it is something you are looking for as well and hopefully they can implement a solution for you soon.