Following the section "5.6. Importing OpenAPI definitions" https://access.redhat.com/documentation/en-us/red_hat_3scale_api_management/2.13/html/operating_3scale/the-threescale-toolbox#importing-openapi-definitions people run podman container without mounting the local OpenAPI file into the container. The toolbox returns error: "File not found: /my/path/spec.json"

Even though podman/docker features should not be documented, and it is better to just link it, many people are running into the same issue.
Here is the podman/docker usage link https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/building_running_and_managing_containers/index . More specifically 5.7. Mounting directory on localhost to the container

Something like this should be the command run by users

$ podman run -v $PWD/my-test-api.json:/tmp/my-test-api.json registry.redhat.io/3scale-amp2/toolbox-rhel8:3scale2.13 3scale import openapi [opts] -d=https://{DEST_KEY}@{3SCALE_ADMIN}-admin.{DOMAIN_NAME}  /tmp/my-test-api.json

In the section 5.3. Importing services, the mounting hint is given.