I use a sitemap to index pages of this site that aren’t linked from the home page.
A sitemap is an XML list of pages I’d like indexed (even if they can’t be crawled from other pgaes). You can find my sitemap here.
Search engines know to look for
sitemap-index.xml (a list of sitemaps) at the root of a site.
If you want to be explicit, you can tell Google where to find yours by uploading it to Search Console.
@astrojs/sitemap to generate mine but it’s a pretty simple XML document structure if you want to generate your own.
It looks like this:
Sitemaps are nice to have but not critical. The work great if you have content you’d like indexed even if not directly linked on your home page.