How to work around "no private data" regression in 13.0.x

A while ago I discovered that the “app data” aka. private data went missing in Nextcloud v13.0.0. I filed an issue for it shortly after. Unfortunately there’s been no activity on the issue for months, and I’m now in a position where I have to find an alternative or fix it.

On the issue, someone says:

we moved this to an app. Please see GitHub - nextcloud/privatedata: OCS Private Data

But it’s not actually in the app store:

Ah mmmit is not in the appstore indeed. I guess we forgot some steps when we moved it to an app.

I can’t really fix this, since it’s not really my app to publish. Can I just download the app itself and install it somehow in my Nextcloud instance? It doesn’t have any installation instructions or releases, so I’m not really sure what to do with it. Or is there some other way I can integrate it into my instance of Nextcloud 13?