As you probably don't like installing node, npm and a ton of packages into your CI, which generates a static hugo page, I created this golang implementation of hugo-lunr. It generates a lunrjs search index from the current working directory.

go install github.com/riesinger/hugo-golunr@latest

cd /path/to/your/site
hugo-golunr

Pretty easy, huh? After running hugo-golunr, you'll see a search_index.json file in your ./static directory. Just load that in your theme.