Where to publish replications of machine learning papers? If I replicated the results of a machine learning paper, is there a website that I can publish my code to that collects informal replication attempts?

https://paperswithcode.com/ allows anyone to publish implementations, but I am looking for something similar that allows anyone to publish implementations along with replicated experimental results. Does such a website exist?
OpenReview (https://openreview.net/) may be what you're looking for. It's both a platform for ML conferences to organize their reviewing process as well as an arXiv-like preprint repository.

One major machine learning conference (ICLR) has been holding "reproducibility challenges," in which participants can submit replication reports of existing papers, but that probably only applies to papers submitted to that conference.

There is a general preprints section, which might be your best bet.

Disclaimer: I used to be on the OpenReview development team