How is it possible with gitlab-ci.yaml to deploy a Next.js commit first to a test branch on Vercel.com?

Then, the same commit needs to be built. This build will call the previously deployed version on Vercel, run tests on it, and if the tests pass, deploy again to Vercel but now on the main branch. SSG methods expect an existing, running endpoint.

I know there are deploy hooks in Vercel that can programmatically trigger deployments, and automatic deployment can be turned off in vercel.json in the project.