Ah, yes that does rule those two unfortunately. I am not aware of any other alternatives providing broader software integration like they do, but it wouldn’t surprise me if some of the big names like LanguageTool would like to, as they already make so many plugins.
Speaking of which, it’s not quite as nice, but those working with Antidote and Scrivener had some interesting ideas for using Scrivener’s external sync folder function, along with a word processor, such as LibreOffice, that does have a plugin.
I use this feature a lot for other reasons, and it is quite useful for certain phases of the project.