Not quite a comparable alternative. I use Pagefind and it's great for static sites but the search is all client side JS, there's no PHP (or otherwise) client to use it's generated index on the server.
A comparable alternative might be TNTSearch: https://github.com/teamtnt/tntsearch though that requires some (common) PHP extensions to be available, which this library does not require.
A comparable alternative might be TNTSearch: https://github.com/teamtnt/tntsearch though that requires some (common) PHP extensions to be available, which this library does not require.