Nextflow does not capture the software required, which is important for reproducibility. Containers are not a solution for this as it only shifts the problem up a level.

My efforts with BioNix (https://github.com/PapenfussLab/bionix) achieve reproducible pipelines by using Nix to capture the software, workflow, and handle execution either locally, on a compute cluster, or HPC.

Guixwl looks similar to BioNix, though BioNix is a thin layer of Nix expressions and Guixwl seems to be more then that and could be more general. BioNix is targeted at bioinformatics and just builds on nixpkgs.