Sodium Plus is open source and under the MIT License, and contributions are very encouraged! Pull requests and issues will be looked at as soon as possible.
We use packwiz to manage mods and assets, so please use it for that too! Their docs are here: https://packwiz.infra.link
To package, use our custom builder tool, which can be used by running ./bld on Linux, or if you are on Windows or MacOS, run make with Go installed, and then find the correct binary for your system in the bin/ folder.
To automatically generate a mod list from all the .pw.toml files in the mods/ and resourcepacks/ folders, use our builder tool with the arguments list --markdown --output MODLIST.md, and it will generate a mod list for you in the MODLIST.md file.
To create changelogs, you can run the python script (changelog.py) to auto-pull all the latest changelogs from Modrinth, but don't modify the CHANGELOG.md from that. That should be manually created. The script will generate a CHANGELIST.md that you can base that off of, but will not be in the repository for others to see.