Currently there is a rules-repo on GitHub but it is missing most of the Sword and Shield data. Could people please download this plugin PluginPile.SwShRulesExporter.dll and add it to their plugins folder? Then open PKHeX and click Tools>SwSh Download Rules Exporter>Export From bak Folder. This will give you a swsh_rules.zip file in the the PKHeX folder which you can upload to here.
Note that if PKHeX hangs and becomes unresponsive during this process that is just because it is going through the whole bak folder and it should complete with a popup message.
Thanks for your assistance in this endeavour and hopefully we can preserve all the rules.
Edit: Updated plugin to flag if no rules were found