Keeping env file in github actions

Question

during migration few projects from gitlab to github I encountered a problem.
In gitlab there is something like file type of env variable. So usually in CI configuration I used eg. kubeconfig file (for connecting with k8s cluster) or SSH private key for ansible (which requires a file as paramater). What is more it was possible to keep these variables on group level so no need to declare variables in each project separately.
Unfortunately there is no such type of env variable as file in github actions. I can encrypt file with gpg and use a passphrase to recreate a kubeconfig/ssh files but it forces me to keeping additional file in each repository.
Do you guys have any idea how to solve this issue? My goal is to keep a file with eg. kubeconfig configuration in one place and be able to use it in many repositories.