Hi @carlo,
This is probably because the pipeline runs in a container/agent that does not have chromium installed.
If you follow Load testing with Jenkins, I would try installing Chromium on the Jenkins job. Or, alternatively, make sure the agents that run those jobs have Chromium installed.
We see similar issues when running with Docker. The k6 image does not yet include chromium; you must install it. See Unable to run xk6-browser binary file inside Docker - GoError: launching browser: exec: no command - #3 by moonbridge. I created my own docker image for the browser to use on a GitLab pipeline a few days back: https://hub.docker.com/repository/docker/immavalls/browser-k6/general. In that one, I install chromium adding RUN apk update && apk add --no-cache chromium.
Make sure to also launch the browser the headless option to true.
I hope this helps. Let us know if you have further questions.
Cheers!