Yes, you can use self-managed GitLab with GitLab Pipelines to build and deploy your Vercel Application.
vercel build allows you to build your project inside GitLab Pipelines, without exposing your source code to Vercel. Then, vercel deploy --prebuilt skips the build step on Vercel and uploads the previously generated .vercel/output folder from the GitLab Pipeline.
Learn more about how to configure GitLab Pipelines and Vercel for custom CI/CD workflows.