Which "commands" can be executed via editor.codeActionsOnSave?

I can't find any clear documentation around this so I'm hoping someone might know the answer. Is the vscode editor.codeActionsOnSave setting able to point to arbitrary commands that are defined by vscode extensions, or can you only use things like source.organizeImports? I'm trying to run a command from an extension that works when triggered via a keyboard shortcut (in this case, vsSharper.sortUsings), but when I add either

"editor.codeActionsOnSave": [ "vsSharper.sortUsings" ]

or

"editor.codeActionsOnSave": {"vsSharper.sortUsings": "always"}

to my settings.json the command isn't run and my using statements are not sorted by the extension. I do not understand why though, since this other extension's documentation seems to indicate this should be possible (this setting being pointed to an extension's command): https://biomejs.dev/reference/vscode/#fix-on-save