In the early stages of development, it makes sense to create an SEO-optimized stub page.

Use Gitlab pages for free frontend hosting

Got to Deploy -> Pages for generate CI scipt or manage page domain

For normal cases (frameworks) CI script should be like:

 image: node:20.12.2-alpine3.19
 before_script:
   - npm ci --ignore-scripts
 pages:
   script:
     - npm run generate
   artifacts:
     paths:
       - public
   rules:
     - if: $CI_COMMIT_BRANCH == "main"

public - should be build destination directory

For SEO do not forget about robot.txt

User-agent: *
Disallow: