Yes, just to confirm there was no off-the-shelf implementation in Rust.

We know the PISA project very well because... it is the fastest engine (though academic) in the tantivy benchmark: https://tantivy-search.github.io/bench/

But I did not know that they were using Partitioned Elias-Fano, maybe the author of the article fulmicoton knew that, I will check that.