Sure, I think distributing 0AD through GOG or Steam would help with the visibility of the game. Most pc-gamer are still on Windows. I don't see how it's a problem that not every platform supports different OS at the moment. It should be possible on Steam. For all the Linux users, it would help to have the latest release version in the repository of some major distros.
Before the WFG team decides to do this, they should appear to be more active. I know you are more active, because I'm here in the forum and I've had a look at gitea/svn/trac. It would help if the web site didn't look like the project was abandoned if you only posted an update once or twice a year. And at the moment the revision log doesn't work either (I checked it because of this post, usually people don't look there when deciding whether to try a new game).
You could easily just post smaller development steps, or when new art is implemented. Just when it's done, not before. Like you did with the Vulkan post or the git migration. That might also help to find some new contributors if you advertise it.
But before that I think 0AD really needs a campaign or a campaign tutorial or at least some more interesting single player content. Petra Bot is fine, but after a while, when you know how it behaves, it gets boring, even when you are not winning.