Over the years I've created lua based dynamic symmetry guides for darktable for personal use. I've been doing a full darktable reconfigure and clean-up lately and realised that those script might be of use to others.
I don't think they fit in the contrib category, but they might make the cut to be added to the third-party projects section on darktable-org/lua-scripts.
Spend the day creating a repository, README.md and added comments etc to the scripts.
https://codeberg.org/Jade_NL/dt.guides Dynamic symmetry guides
I'll notice soon enough if there's any interest in adding this. Let me know if there is interest but something needs to be changed or is unclear.