See the bitrise.yml for an example setup, using https://github.com/TestArmada/flank on https://www.bitrise.io/
The config requires the following variables to be set as Secrets:
SERVICE_ACCOUNT_KEY_JSON: the Google (Firebase) Service Account JSONGOOGLE_CLOUD_PROJECT: the Firebase google project name/id
Note: if you'd get an error like Test run failed to complete. Expected 786 tests, received 660 that can mean that the test app is not orchestrator compatible. If that's the case simply change the use-orchestrator: true to use-orchestrator: false in the Flank config (flank.yml) and it'll work.