Author of peek here. Honestly, I got burnt out. We stopped using this internally at GitHub for our secondary Rails applications which made it difficult to continue working on. Rails was going through its identity crisis with asset pipelines and I didn't feel like trying to support every available option for people like Sprockets, Importmaps, NPM, Bower, etc. It was nice when there was the paved path and users could generally follow the README and be up and running quickly.
https://github.com/MiniProfiler/rack-mini-profiler gets you most of the way there and comes by default in the Gemfile for new Rails applications.