Depends how complex you want. Jekyll --watch is fine for testing blogs and reloads very fast with --incremental builds. We have it set up with a self hosted netlify for editors - updates get pushed to a repo by netlify, the repo is watched by Google cloud build and the site is automatically updated on save. All on free tier services. Frequent updates will hammer the build server (if you build on each push) so could eg push to a dev branch and merge-to-main with a cron job every so often.

You could run a dev server and port forward the preview if necessary.