I recommend setting up Seleniums Docker solution. I use that to run Behat tests in, you can define multiple profiles in the behat.yml file. Using Chrome driver, each profile an be a different device emulation mode in Chrome. Then when you run behat - just pass a runtime arg telling it which profile to use.
I also recommend checking out the Drupal Behat Extension.
You may also want to look into visual regression testing as well.